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  • 1.
    Abrahamsson, Maria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Lundqvist, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    Wolpher, Henriette
    Johansson, Olof
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Eriksson, Lars
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Rasmussen, Torben
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
    Becker, Hans-Christian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Photochemistry and Molecular Science.
    Norrby, Per-Ola
    Åkermark, Björn
    Persson, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Quantum Chemistry.
    Steric influence on the excited-state lifetimes of ruthenium complexes with bipyridyl-alkanylene-pyridyl ligands.2008In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 47, no 9, p. 3540-3548Article in journal (Refereed)
    Abstract [en]

    The structural effect on the metal-to-ligand charge transfer (MLCT) excited-state lifetime has been investigated in bis-tridentate Ru(II)-polypyridyl complexes based on the terpyridine-like ligands [6-(2,2'-bipyridyl)](2-pyridyl)methane (1) and 2-[6-(2,2'-bipyridyl)]-2-(2-pyridyl)propane (2). A homoleptic ([Ru(2)(2)](2+)) and a heteroleptic complex ([Ru(ttpy)(2)](2+)) based on the new ligand 2 have been prepared and their photophysical and structural properties studied experimentally and theoretically and compared to the results for the previously reported [Ru(1)(2)](2+). The excited-state lifetime of the homoleptic Ru-II complex with the isopropylene-bridged ligand 2 was found to be 50 times shorter than that of the corresponding homoleptic Ru-II complex of ligand 1, containing a methylene bridge. A comparison of the ground-state geometries of the two homoleptic complexes shows that steric interactions involving the isopropylene bridges make the coordination to the central Ru-II ion less octahedral in [Ru(2)(2)](2+) than in [Ru(1)(2))(2+). Calculations indicate that the structural differences in these complexes influence their ligand field splittings as well as the relative stabilities of the triplet metal-to-ligand charge transfer ((MLCT)-M-3) and metal-centered ((MC)-M-3) excited states. The large difference in measured excited-state lifetimes for the two homoleptic Ru-II complexes is attributed to a strong influence of steric interactions on the ligand field strength, which in turn affects the activation barriers for thermal conversion from (MLCT)-M-3 states to short-lived (MC)-M-3 states.

  • 2.
    Abujrais, Sandy
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry. Uppsala Univ, ME CFS Collaborat Res Ctr, Uppsala, Sweden..
    Ubhayasekera, S.J. Kumari A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry. Uppsala Univ, ME CFS Collaborat Res Ctr, Uppsala, Sweden..
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry. Uppsala Univ, ME CFS Collaborat Res Ctr, Uppsala, Sweden..
    Analysis of tryptophan metabolites and related compounds in human and murine tissue: development and validation of a quantitative and semi-quantitative method using high resolution mass spectrometry2024In: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 16, no 7, p. 1074-1082Article in journal (Refereed)
    Abstract [en]

    This study explores the metabolic differences between human and murine plasma in addition to differences between murine subcutaneous and visceral white adipose tissue. A quantitative and semi-quantitative targeted method was developed and validated for this purpose. The quantitative method includes tryptophan and its metabolites in addition to tyrosine, phenylalanine, taurine, B vitamins, neopterin, cystathionine and hypoxanthine. While the semi-quantitative method includes; 3-indoleacetic acid, 5-hydroxyindoleacetic acid, acetylcholine, asymmetric dimethylarginine, citrulline and methionine. Sample preparation was based on protein precipitation, while quantification was conducted using ultrahigh-performance liquid chromatography coupled to a quadrupole Orbitrap tandem mass spectrometer with electrospray ionization in the parallel reaction monitoring (PRM) mode. The low limit of quantification for all metabolites ranged from 1 to 200 ng mL-1. Matrix effects and recoveries for stable isotope labelled internal standards were evaluated, with most having a coefficient of variation (CV) of less than 15%. Results showed that a majority of the analytes passed both the intra- and interday precision and accuracy criteria. The comparative analysis of human and murine plasma metabolites reveals species-specific variations within the tryptophan metabolic pathway. Notably, murine plasma generally exhibits elevated concentrations of most compounds in this pathway, with the exceptions of kynurenine and quinolinic acid. Moreover, the investigation uncovers noteworthy metabolic disparities between murine visceral and subcutaneous white adipose tissues, with the subcutaneous tissue demonstrating significantly higher concentrations of tryptophan, phenylalanine, tyrosine, and serotonin. The findings also show that even a semi-quantitative method can provide comparable results to quantitative methods from other studies and be effective for assessing metabolites in a complex sample. Overall, this study provides a robust platform to compare human and murine metabolism, providing a valuable insight to future investigations. A validated HRMS method for measuring tryptophan metabolites and related compounds has been developed, with simple sample preparation, successfully applied in human and murine plasma, as well as murine white adipose tissue.

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  • 3. Abuzooda, Thana
    et al.
    Amini, Ahmad
    Swedish Drug Agency,751 03 Uppsala, Sweden.
    Abdel-Rehim, Mohamed
    Graphite-based microextraction by packed sorbent for online extraction of β-blockers from human plasma samples2015In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 992, p. 86-90Article in journal (Refereed)
    Abstract [en]

    In the present work a new graphitic material (Carbon-XCOS) was used as a sorbent for microextraction by packed sorbent (MEPS). The β-blockers metoprolol and acebutolol in plasma samples were extracted and detected online using Carbon-MEPS syringe and liquid chromatography and tandem mass spectrometry (LC-MS/MS). Factors affecting the MEPS performance such as conditioning, washing and elution solutions were investigated. The validation of the bioanalytical method was performed using human plasma. The standard curve ranged from 10 to 2000nM and the lower limit of quantification (LLOQ) was set to 10nM. The method validation showed good accuracy and precision for the quality control (QC) samples at three concentration levels (30, 800 and 1600nM). The accuracy values of the QC samples were in the range of 86-108% (n=18). The precision values of intra- and inter-day for QC samples ranged from 4.4% to 14.4% (RSD) for the both studied analytes. The coefficient of determination (R(2)) values were ≥0.999 (n=3).

  • 4.
    Aerts, Jordan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Capillary electrophoresis mass spectrometry applied to structural proteomics and small molecule analysis2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Capillary electrophoresis with mass spectrometric (CE–MS) detection offers a separation method without equal in terms of flexibility, utility, and cost efficiency. Here we demonstrate precisely this through the application of several laboratory-built CE–MS instruments for the separation of brain metabolites in non-primates, enantioselective separations of synthetic anesthetic metabolites in fractionated pony urine, application in structural proteomics workflows, and identification of exogenous alkaloid biotransformationproducts in human cerebrospinal fluid (CSF).

    We outline a method for quickly and affordably etching austenitic steel tubing, which is widely used in electrospray sources for CE–MS. The stainless steel tapered tip emitters provide robust electrospray with low sheath liquid flow rates and can be easily fabricated in-house, offering flexibility and cost-efficiency when commercial options areunavailable. We contribute a CE–MS method for enantiomer separation, specifically targeting 6-hydroxynorketamine (HNK). By introducing chiral selectors into the separation capillary, the method enables efficient enantiomer separation and offers a newtool to assist with research on HNK as a cure for depression.

    We explore the feasibility of cold CE–MS in hydrogen deuterium exchange workflows. The utilization of a lab-designed Peltier-cooled CE device achieves deuterium back exchange rates on par with commercial liquid chromatography-based platforms, offering new possibilities for studying protein structures and interactions.

    We also demonstrate the wide ranging versatility of CE–MS with contributions to the identification of specific tobacco related metabolites in CSF samples during the development of a high throughput mass spectrometry diagnostic tool for Parkinson’sDisease.

    This thesis showcases the versatility and value of CE–MS in various applications, a true blessing for analytical chemistry.

    List of papers
    1. Enantioselective CE–MS analysis of ketamine metabolites in urine
    Open this publication in new window or tab >>Enantioselective CE–MS analysis of ketamine metabolites in urine
    Show others...
    2023 (English)In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 44, no 1-2, p. 125-134Article in journal (Refereed) Published
    Abstract [en]

    The chiral drug ketamine has long-lasting antidepressant effects with a fast onset and is also suitable to treat patients with therapy-resistant depression. The metabolite hydroxynorketamine (HNK) plays an important role in the antidepressant mechanism of action. Hydroxylation at the cyclohexanone ring occurs at positions 4, 5, and 6 and produces a total of 12 stereoisomers. Among those, the four 6HNK stereoisomers have the strongest antidepressant effects. Capillary electrophoresis with highly sulfated γ-cyclodextrin (CD) as a chiral selector in combination with mass spectrometry (MS) was used to develop a method for the enantioselective analysis of HNK stereoisomers with a special focus on the 6HNK stereoisomers. The partial filling approach was applied in order to avoid contamination of the MS with the chiral selector. Concentration of the chiral selector and the length of the separation zone were optimized. With 5% highly sulfated γ-CD in 20 mM ammonium formate with 10% formic acid and a 75% filling the four 6HNK stereoisomers could be separated with a resolution between 0.79 and 3.17. The method was applied to analyze fractionated equine urine collected after a ketamine infusion and to screen the fractions as well as unfractionated urine for the parent drug ketamine and other metabolites, including norketamine and dehydronorketamine.

    Place, publisher, year, edition, pages
    Wiley-VCH Verlagsgesellschaft, 2023
    Keywords
    capillary electrophoresis–mass spectrometry, chiral separation, hydroxynorketamine, ketamine, partial filling
    National Category
    Analytical Chemistry Pharmaceutical Sciences
    Identifiers
    urn:nbn:se:uu:diva-498086 (URN)10.1002/elps.202200175 (DOI)000895479000001 ()36398998 (PubMedID)
    Funder
    Swedish Foundation for Strategic Research, RIF14‐0078Swedish Foundation for Strategic Research, ICA16‐0010Science for Life Laboratory, SciLifeLabSwedish Research Council, 2018-03320Swedish Research Council, 2018-05501Swedish Research Council, 2018-03988Åke Wiberg Foundation
    Available from: 2023-03-09 Created: 2023-03-09 Last updated: 2023-10-29Bibliographically approved
    2. Electrochemically Etched Tapered-Tip Stainless-Steel Electrospray-Ionization Emitters for Capillary Electrophoresis-Mass Spectrometry
    Open this publication in new window or tab >>Electrochemically Etched Tapered-Tip Stainless-Steel Electrospray-Ionization Emitters for Capillary Electrophoresis-Mass Spectrometry
    2023 (English)In: Journal of Proteome Research, ISSN 1535-3893, E-ISSN 1535-3907, Vol. 22, no 4, p. 1377-1380Article in journal (Refereed) Published
    Abstract [en]

    We have used household consumables to facilitate electrochemical etching of stainless-steel hypodermic tubing to produce tapered-tip emitters suitable for electrospray ionization for use in mass spectrometry. The process involves the use of 1% oxalic acid and a 5 W USB power adapter, commonly known as a phone charger. Further, our method avoids the otherwise commonly used strong acids that entail chemical hazards: concentrated HNO3 for etching stainless steel, or concentrated HF for etching fused silica. Hence, we here provide a convenient and self-inhibiting procedure with minimal chemical hazards to manufacture tapered-tip stainless-steel emitters. We show its performance in metabolomic analysis with CE-MS of a tissue homogenate where the metabolites acetylcarnitine, arginine, carnitine, creatine, homocarnosine, and valerylcarnitine were identified, all with basepeak separated electropherograms, within <6 min of separation. The mass spectrometry data are freely available through the MetaboLight public data repository via access number MTBLS7230.

    Place, publisher, year, edition, pages
    American Chemical Society (ACS), 2023
    Keywords
    electrochemical etching, tapered tip, stainless-steel emitter, electrospray ionization, CE-MS
    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-501588 (URN)10.1021/acs.jproteome.3c00076 (DOI)000944534000001 ()36866861 (PubMedID)
    Funder
    Swedish Research Council, 2021-03293Swedish Foundation for Strategic Research, ICA16-0010Science for Life Laboratory, SciLifeLabSwedish Research Council, 2022-04198Swedish Research Council, 2018-03988Åke Wiberg Foundation
    Available from: 2023-05-12 Created: 2023-05-12 Last updated: 2023-10-29Bibliographically approved
    3. Zero-Degree Celsius Capillary Electrophoresis Electrospray Ionization for Hydrogen Exchange Mass Spectrometry
    Open this publication in new window or tab >>Zero-Degree Celsius Capillary Electrophoresis Electrospray Ionization for Hydrogen Exchange Mass Spectrometry
    2023 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, ISSN 0003-2700, Vol. 95, no 2, p. 1149-1158Article in journal (Refereed) Published
    Abstract [en]

    Currently, fast liquid chromatographic separations at low temperatures are exclusively used for the separation of peptides generated in hydrogen deuterium exchange (HDX) workflows. However, it has been suggested that capillary electrophoresis may be a better option for use with HDX. We performed in solution HDX on peptides and bovine hemoglobin (Hb) followed by quenching, pepsin digestion, and cold capillary electrophoretic separation coupled with mass spectrometry (MS) detection for benchmarking a laboratory-built HDX–MS platform. We found that capillaries with a neutral coating to eliminate electroosmotic flow and adsorptive processes provided fast separations with upper limit peak capacities surpassing 170. In contrast, uncoated capillaries achieved 30% higher deuterium retention for an angiotensin II peptide standard owing to faster separations but with only half the peak capacity of coated capillaries. Data obtained using two different separation conditions on peptic digests of Hb showed strong agreement of the relative deuterium uptake between methods. Processed data for denatured versus native Hb after deuterium labeling for the longest timepoint in this study (50,000 s) also showed agreement with subunit interaction sites determined by crystallographic methods. All proteomic data are available under DOI: 10.6019/PXD034245.

    Place, publisher, year, edition, pages
    Springer Nature, 2023
    National Category
    Analytical Chemistry
    Research subject
    Chemistry with specialization in Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-498084 (URN)10.1021/acs.analchem.2c03893 (DOI)
    Funder
    Science for Life Laboratory, SciLifeLabSwedish Research Council, 2018-03320Swedish Research Council, 2018-03988Swedish Research Council, 2018-05501Åke Wiberg Foundation
    Available from: 2023-03-09 Created: 2023-03-09 Last updated: 2024-01-15
    4. Rapid metabolic profiling of one microliter crude CSF by MALDI MS can differentiate de novo Parkinson’s disease
    Open this publication in new window or tab >>Rapid metabolic profiling of one microliter crude CSF by MALDI MS can differentiate de novo Parkinson’s disease
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Parkinson’s disease (PD) is a highly prevalent neurodegenerative disorder affecting the motor system. However, the correct diagnosis of PD and atypical parkinsonism may be difficult, with high clinical uncertainty. The disease is diagnosed solely based on the presence of clinical symptoms, and there is an urgent need to identify reliable biomarkers using high-throughput, molecular-specific methods to improve current diagnostics. Here, we present a matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) method that requires minimal sample preparation and only one µl of crude cerebrospinal fluid (CSF). The method enables analysis of hundreds of samples in a single experiment while simultaneously detecting numerous metabolites with sub-ppm mass accuracy. To test the method, we analyzed CSF samples from 12 de novo PD patients (that is, newly diagnosed and previously untreated) and 12 age-matched controls. Within the identified molecules, we found neurotransmitters and their metabolites, such as γ-aminobutyric acid, 3-methoxytyramine, homovanillic acid, serotonin, histamine, amino acids, and metabolic intermediates. Limits of detection were estimated for multiple neurotransmitters with high linearity (R2 > 0.99) and sensitivity (as low as 16 pg/µl). Application of multivariate classification led to a highly significant (P <0.001) model of PD prediction with 100% classification rate, which was further thoroughly validated with permutation test and univariate analysis. Molecules related to the neuromelanin pathway were found to be increased in the PD group. Our method enables rapid detection of PD-related biomarkers in low sample volumes and could serve as a valuable tool in the development of robust PD diagnostics.

    National Category
    Natural Sciences
    Research subject
    Clinical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-514776 (URN)
    Available from: 2023-10-23 Created: 2023-10-23 Last updated: 2023-10-29
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  • 5.
    Aerts, Jordan
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Andrén, Per E.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Jansson, Erik T.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Electrochemically Etched Tapered-Tip Stainless-Steel Electrospray-Ionization Emitters for Capillary Electrophoresis-Mass Spectrometry2023In: Journal of Proteome Research, ISSN 1535-3893, E-ISSN 1535-3907, Vol. 22, no 4, p. 1377-1380Article in journal (Refereed)
    Abstract [en]

    We have used household consumables to facilitate electrochemical etching of stainless-steel hypodermic tubing to produce tapered-tip emitters suitable for electrospray ionization for use in mass spectrometry. The process involves the use of 1% oxalic acid and a 5 W USB power adapter, commonly known as a phone charger. Further, our method avoids the otherwise commonly used strong acids that entail chemical hazards: concentrated HNO3 for etching stainless steel, or concentrated HF for etching fused silica. Hence, we here provide a convenient and self-inhibiting procedure with minimal chemical hazards to manufacture tapered-tip stainless-steel emitters. We show its performance in metabolomic analysis with CE-MS of a tissue homogenate where the metabolites acetylcarnitine, arginine, carnitine, creatine, homocarnosine, and valerylcarnitine were identified, all with basepeak separated electropherograms, within <6 min of separation. The mass spectrometry data are freely available through the MetaboLight public data repository via access number MTBLS7230.

    Download full text (pdf)
    fulltext
  • 6.
    Aerts, Jordan
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Department of Pharmaceutical Biosciences, Uppsala University, Uppsala751 24, Sweden.
    Andrén, Per E.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences, MMS, Medical Mass Spectrometry. Uppsala University, Science for Life Laboratory, SciLifeLab. Department of Pharmaceutical Biosciences, Uppsala University, Uppsala751 24, Sweden;Science for Life Laboratory, Spatial Mass Spectrometry, Uppsala University, Uppsala751 24, Sweden.
    Jansson, Erik T.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Department of Pharmaceutical Biosciences, Uppsala University, Uppsala751 24, Sweden.
    Zero-Degree Celsius Capillary Electrophoresis Electrospray Ionization for Hydrogen Exchange Mass Spectrometry2023In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, ISSN 0003-2700, Vol. 95, no 2, p. 1149-1158Article in journal (Refereed)
    Abstract [en]

    Currently, fast liquid chromatographic separations at low temperatures are exclusively used for the separation of peptides generated in hydrogen deuterium exchange (HDX) workflows. However, it has been suggested that capillary electrophoresis may be a better option for use with HDX. We performed in solution HDX on peptides and bovine hemoglobin (Hb) followed by quenching, pepsin digestion, and cold capillary electrophoretic separation coupled with mass spectrometry (MS) detection for benchmarking a laboratory-built HDX–MS platform. We found that capillaries with a neutral coating to eliminate electroosmotic flow and adsorptive processes provided fast separations with upper limit peak capacities surpassing 170. In contrast, uncoated capillaries achieved 30% higher deuterium retention for an angiotensin II peptide standard owing to faster separations but with only half the peak capacity of coated capillaries. Data obtained using two different separation conditions on peptic digests of Hb showed strong agreement of the relative deuterium uptake between methods. Processed data for denatured versus native Hb after deuterium labeling for the longest timepoint in this study (50,000 s) also showed agreement with subunit interaction sites determined by crystallographic methods. All proteomic data are available under DOI: 10.6019/PXD034245.

  • 7.
    Aerts, Jordan T.
    et al.
    Beckman Institute for Advanced Science and Technology, ‡Department of Pharmacology, §Department of Molecularand Integrative Physiology, ∥Department of Chemistry, and ⊥Neuroscience Program, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States.
    Louis, Kathleen R.
    Beckman Institute for Advanced Science and Technology, ‡Department of Pharmacology, §Department of Molecularand Integrative Physiology, ∥Department of Chemistry, and ⊥Neuroscience Program, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States.
    Crandall, Shane R.
    Beckman Institute for Advanced Science and Technology, ‡Department of Pharmacology, §Department of Molecularand Integrative Physiology, ∥Department of Chemistry, and ⊥Neuroscience Program, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States.
    Govindaiah, Gubbi
    Beckman Institute for Advanced Science and Technology, ‡Department of Pharmacology, §Department of Molecularand Integrative Physiology, ∥Department of Chemistry, and ⊥Neuroscience Program, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States.
    Cox, Charles L.
    Beckman Institute for Advanced Science and Technology, ‡Department of Pharmacology, §Department of Molecularand Integrative Physiology, ∥Department of Chemistry, and ⊥Neuroscience Program, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States.
    Sweedler, Jonathan V.
    Beckman Institute for Advanced Science and Technology, ‡Department of Pharmacology, §Department of Molecularand Integrative Physiology, ∥Department of Chemistry, and ⊥Neuroscience Program, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States.
    Patch Clamp Electrophysiology and Capillary Electrophoresis–Mass Spectrometry Metabolomics for Single Cell Characterization2014In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 86, no 6, p. 3203-3208Article in journal (Refereed)
  • 8.
    Aghoutane, Youssra
    et al.
    Biotechnology Agroalimentary and Biomedical Analysis Group, Department of Biology, Faculty of Sciences, Moulay Ismaïl University, B.P. 11201, Zitoune, Meknes, Morocco; Sensor Electronic & Instrumentation Group, Department of Physics, Faculty of Sciences, Moulay Ismaïl University, B.P. 11201, Zitoune, Meknes, Morocco.
    Diouf, Alassane
    Biotechnology Agroalimentary and Biomedical Analysis Group, Department of Biology, Faculty of Sciences, Moulay Ismaïl University, B.P. 11201, Zitoune, Meknes, Morocco; Sensor Electronic & Instrumentation Group, Department of Physics, Faculty of Sciences, Moulay Ismaïl University, B.P. 11201, Zitoune, Meknes, Morocco.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Bouchikhi, Benachir
    Sensor Electronic & Instrumentation Group, Department of Physics, Faculty of Sciences, Moulay Ismaïl University, B.P. 11201, Zitoune, Meknes, Morocco.
    El Bari, Nezha el bari
    Biotechnology Agroalimentary and Biomedical Analysis Group, Department of Biology, Faculty of Sciences, Moulay Ismaïl University, B.P. 11201, Zitoune, Meknes, Morocco.
    Development of a molecularly imprinted polymer electrochemical sensor and its application for sensitive detection and determination of malathion in olive fruits and oils2020In: Bioelectrochemistry, ISSN 1567-5394, E-ISSN 1878-562X, Vol. 132, article id 107404Article in journal (Refereed)
    Abstract [en]

    Malathion (MAL) is an organophosphorus (OP) insecticide. It is a cholinesterase inhibitor, 15 which can pose serious health and environmental problems. In this study, a sensitive and 16 selective molecular imprinted polymer (MIP) based on screen-printed gold electrodes (Au-17 SPE) for MAL detection in olive oils and fruits, was devised. The MIP sensor was prepared 18 using acrylamide as the functional monomer and MAL as the template. Subsequently, the 19 morphology of the electrode surface was studied by scanning electron microscopy (SEM) and 20 atomic force microscopy (AFM). The electrochemical characterization of the developed MIP 21 sensor was performed by cyclic voltammetry (CV), differential pulse voltammetry (DPV), 22 and electrochemical impedance spectroscopy (EIS) techniques. The operational repeatability 23 and stability of the sensor were studied. It was found to have a dynamic concentration range 24 of (0.1 pg mL-1-1000 pg mL-1) and a low limit of detection (LOD) of 0.06 pg mL-1. 25 Furthermore, the sensor was employed to determine MAL content in olive oil with a recovery 26 rate of 87.9% and a relative standard deviation of 8%. It was successfully applied for MAL 27 determination in real samples and promise to open new opportunities for the detection of OP 28 pesticides residues in various food products, as well as in environmental applications.

  • 9.
    Ahlgren, Joakim
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry.
    Reitzel, Kasper
    Danielsson, Rolf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry.
    Gogoll, Adolf
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Rydin, Emil
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry. Department of Biochemistry and Organic Chemistry, Organic Chemistry I. Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Biogenic phosphorus in oligotropic mountain lake sediments: Differences in composition measured with NMR spectroscopy2006In: Water Research, no 40, p. 3705-3712Article in journal (Refereed)
  • 10.
    Ahlgren, Joakim
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Tranvik, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Waldebäck, Monica
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Markides, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Rydin, Emil
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Limnology.
    Sediment Depth Attenuation of Biogenic Phosphorus Compounds Measured by 31P NMR2005In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 39, no 3, p. 867-872Article in journal (Refereed)
    Abstract [en]

    Being a major cause of eutrophication and subsequent loss of water quality, the turnover of phosphorus (P) in lake sediments is in need of deeper understanding. A major part of the flux of P to eutrophic lake sediments is organically bound or of biogenic origin. This P is incorporated in a poorly described mixture of autochthonous and allochthonous sediment and forms the primary storage of P available for recycling to the water column, thus regulating lake trophic status. To identify and quantify biogenic sediment P and assess its lability, we analyzed sediment cores from Lake Erken, Sweden, using traditional P fractionation, and in parallel, NaOH extracts were analyzed using 31P NMR. The surface sediments contain orthophosphates (ortho-P) and pyrophosphates (pyro-P), as well as phosphate mono- and diesters. The first group of compounds to disappear with increased sediment depth is pyrophosphate, followed by a steady decline of the different ester compounds. Estimated half-life times of these compound groups are about 10 yr for pyrophosphate and 2 decades for mono- and diesters. Probably, these compounds will be mineralized to ortho-P and is thus potentially available for recycling to the water column, supporting further growth of phytoplankton. In conclusion, 31P NMR is a useful tool to asses the bioavailability of certain P compound groups, and the combination with traditional fractionation techniques makes quantification possible.

  • 11.
    Ahlgren, Sara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Fondell, Amelie
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Gedda, Lars
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Medical Radiation Science. Swedish Radiat Safety Author, Res Unit, Solna Strandvag 96, SE-17116 Stockholm, Sweden.
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    EGF-targeting lipodisks for specific delivery of poorly water-soluble anticancer agents to tumour cells2017In: RSC Advances, E-ISSN 2046-2069, Vol. 7, no 36, p. 22178-22186Article in journal (Refereed)
    Abstract [en]

    Concerns regarding poor aqueous solubility, high toxicity and lack of specificity impede the translation of many hydrophobic anticancer agents into safe and effective anticancer drugs. The application of colloidal drug delivery systems, and in particular the use of lipid-based nanocarriers, has been identified as a promising means to overcome these issues. PEG-stabilized lipid nanodisks (lipodisks) have lately emerged as a novel type of biocompatible, nontoxic and adaptable drug nanocarrier. In this study we have explored the potential of lipodisks as a platform for formulation and tumour targeted delivery of hydrophobic anticancer agents. Using curcumin as a model compound, we show that lipodisks can be loaded with substantial amounts of hydrophobic drugs (curcumin/lipid molar ratio 0.15). We demonstrate moreover that by deliberate choice of preparation protocols the lipodisks can be provided with relevant amounts of targeting proteins, such as epidermal growth factor (EGF). Data from in vitro cell studies verify that such EGF-decorated curcumin-loaded lipodisks are capable of EGF-receptor specific targeting of human A-431 tumour cells, and strongly suggest that the interaction between the lipodisks and the tumour cells results in receptor-mediated internalization of the disks and their cargo.

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  • 12.
    Ahmed, Hytham
    et al.
    Menoufia Univ, Dept Pharmaceut Anal, Menofia Governorate, Al Minufiyah, Egypt..
    Wahbi, Abdel-Aziz
    Univ Alexandria, Dept Pharmaceut Analyt Chem, Alexandria 21521, Egypt..
    Elmongy, Hatem
    Univ Alexandria, Dept Pharmaceut Analyt Chem, Alexandria 21521, Egypt..
    Amini, Ahmad
    Swedish Drug Agcy, Uppsala, Sweden..
    Koyi, Hirsh
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Disciplinary Domain of Medicine and Pharmacy, research centers etc., Centre for Research and Development, Gävleborg. Cty Council Gävleborg, Med Gävle Hosp, Dept Resp Med, Gävle, Sweden.
    Brandén, Eva
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Disciplinary Domain of Medicine and Pharmacy, research centers etc., Centre for Research and Development, Gävleborg. Cty Council Gävleborg, Med Gävle Hosp, Dept Resp Med, Gävle, Sweden.
    Abdel-Rehim, Mohamed
    Karolinska Inst, SE-17176 Solna, Sweden..
    Determination and Pharmacokinetics of Omeprazole Enantiomers in Human Plasma and Oral Fluid Utilizing Microextraction by Packed Sorbent and Liquid Chromatography-Tandem Mass Spectrometry2021In: International Journal of Analytical Chemistry, ISSN 1687-8760, E-ISSN 1687-8779, Vol. 2021, article id 8845139Article in journal (Refereed)
    Abstract [en]

    In the present work, the determination of omeprazole (OME) enantiomers in oral fluid and plasma samples was carried out utilizing microextraction by packed sorbent (MEPS) and liquid chromatography-tandem mass spectrometry. A chiral column with cellulose-SB phase was used for the first time for enantiomeric separation of OME with an isocratic elution system using 0.2% ammonium hydroxide in hexane-ethanol mixture (70 : 30, v/v) as the mobile phase. OME enantiomers were determined utilizing a triple quadrupole tandem mass spectrometer in positive ion mode (ESI+) monitoring mass transitions: m/z 346.3 -> 198.0 for OME and m/z 369.98 -> 252.0 for internal standard. The limits of detection and quantification of the present method for both enantiomers were 0.1 and 0.4 ng/mL, respectively. The method validation provided good accuracy and precision. The matrix effect factor was less than 5%, and no interfering peaks were observed. The interday precision values ranged from 2.2 to 7.5 (%RSD), and the accuracy of determinations varied from -9.9% to 8.3%. In addition, the pharmacokinetics (PK) of omeprazole enantiomers in healthy subjects after a single oral dose was investigated. (S)-Enantiomers showed higher levels than (R)-enantiomers throughout 24 h. It was found that the mean maximum concentrations of (R)- and (S)-omeprazole in plasma samples were about two times higher than in oral fluid.

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  • 13.
    Ali, Sajid
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Koehler, Jonas K.
    Univ Freiburg, Inst Pharmaceut Sci, D-79104 Freiburg, Germany..
    Silva, Luís
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Gedda, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Massing, Ulrich
    Univ Freiburg, Inst Pharmaceut Sci, D-79104 Freiburg, Germany.;Andreas Hettich GmbH & Co KG, D-78532 Tuttlingen, Germany..
    Edwards, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Dual centrifugation as a novel and efficient method for the preparation of lipodisks2024In: International Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 653, article id 123894Article in journal (Refereed)
    Abstract [en]

    Polyethylene glycol (PEG)-stabilized lipodisks have emerged as innovatiive, promising nanocarriers for several classes of drugs. Prior research underscores the important role of lipid composition and preparation method in determining the lipodisk size, uniformity, and drug loading capacity. In this study, we investigate dual centrifugation (DC) as a novel technique for the production of PEG-stabilized lipodisks. Moreover, we explore the potential use of DC for the encapsulation of two model drugs, curcumin and doxorubicin, within the disks. Our results show that by a considerate choice of experimental conditions, DC can be used as a fast and straightforward means to produce small and homogenous lipodisks with a hydrodynamic diameter of 20-30 nm. Noteworthy, the technique works well for the production of both cholesterol-free and cholesterol-containing disks and does not require pre-mixing of the lipids in organic solvent. Furthermore, our investigations confirm the efficacy of DC in formulating curcumin and doxorubicin within these lipodisks. For doxorubicin, careful control and optimization of the experimental conditions resulted in formulations displaying an encouraging encapsulation efficiency of 84 % and a favourable drug-to-lipid ratio of 0.13 in the disks.

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  • 14.
    Allard, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Metabolic Studies with Liquid Separation Coupled to Mass Spectrometry2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Metabolism is the sum of all chemical processes with the purpose to maintain life, as well as enable reproduction, in a living organism. Through the study of metabolism, increased understanding of pharmacological mechanisms and diseases can be achieved. This thesis describes several ways of doing so, including targeted analysis of selected metabolites and investigations of systematic metabolic differences between selected groups through pattern recognition.

    A method for exploring metabolic patterns in urine samples after intake of coffee or tea was developed. The methodology was later used with the aim to find biomarkers for prostate cancer and urinary bladder cancer.

    Furthermore, a fully automated quantitative method was developed for concentration measurements of the double prodrug ximelagatran and its metabolites in pig liver. The method was then used to study the roll of active transporters in pig liver cells.

    Moreover, a fundamental study was conducted to investigate how monitoring of small, doubly charged analytes can improve the limit of detection and precision in a quantitative method.

    The techniques used for the experiments were liquid separation coupled to electrospray mass spectrometry. Extra efforts were made to make the separation and the ionization as compatible as possible to each other for increased quality of the collected data.

    List of papers
    1. Comparing capillary electrophoresis: mass spectrometry fingerprints of urine samples obtained after intake of coffee, tea, or water.
    Open this publication in new window or tab >>Comparing capillary electrophoresis: mass spectrometry fingerprints of urine samples obtained after intake of coffee, tea, or water.
    Show others...
    2008 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 80, no 23, p. 8946-8955Article in journal (Refereed) Published
    Abstract [en]

    Metabolomic fingerprinting is a growing strategy for characterizing complex biological samples without detailed prior knowledge about the metabolic system. A two-way analysis system with liquid separation and mass spectrometric detection provides detail-rich data suitable for such fingerprints. As a model study, human urine samples, obtained after intake of coffee, tea, or water, were analyzed with capillary electrophoresis electrospray ionization time-of-flight mass spectrometry (CE−ESI-TOF-MS). In-house-developed software (in Matlab) was utilized to manage and explore the large amount of data acquired (230 CE−MS runs, each with 50−100 million nonzero data points). After baseline and noise reduction, followed by suitable binning in time and m/z, the data sets comprised 9 and 14 million data points in negative and positive ESI mode, respectively. Finally, a signal threshold was applied, further reducing the number to about 100 000 data points per data set. A set of interactive exploratory tools, utilizing principal component analysis (PCA) and analysis of variance (ANOVA) results based on a general linear model, facilitated visual interpretation with score plots (for group assessment) and differential fingerprints (for “hot spot” detection). In the model study highly significant differences due to beverage intake were obtained among the 10 first principal components (p < 10−6 for two of the components in both ESI modes). Especially, the contrasts between “coffee” and “tea or water” indicated several “hot spots” with highly elevated intensities (e.g., for uncharged masses 93, 94, 109, 119, 123, 132, 148, 169, 178, 187, 190, and 193) suitable for further analysis, for example, with tandem MS.

    National Category
    Analytical Chemistry
    Research subject
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-100706 (URN)10.1021/ac801012y (DOI)000261335600015 ()18954082 (PubMedID)
    Available from: 2009-04-06 Created: 2009-04-06 Last updated: 2022-01-28Bibliographically approved
    2. Online capillary solid phase extraction and liquid chromatographic separation with quantitative tandem mass spectrometric detection (SPE-LC-MS/MS) of ximelagatran and its metabolites in a complex matrix.
    Open this publication in new window or tab >>Online capillary solid phase extraction and liquid chromatographic separation with quantitative tandem mass spectrometric detection (SPE-LC-MS/MS) of ximelagatran and its metabolites in a complex matrix.
    Show others...
    2009 (English)In: Journal of chromatography. B, ISSN 1570-0232, E-ISSN 1873-376X, Vol. 877, no 3, p. 291-297Article in journal (Refereed) Published
    Abstract [en]

    This work presents the development and validation of a fully automated quantitative analysis method of melagatran, its prodrug ximelagatran, and its major metabolites for the study of drug behavior in biofluids. The method involves online sample clean-up and enrichment on a C4 capillary column followed by separation on a capillary C18 column. Electrospray ionization tandem mass spectrometric detection in positive ion mode was performed with multiple reactions monitoring of eight different transients, divided into two time segments with four transients each. The structural similarity, the complexity of the matrix (pig liver extract) and the formation of isobaric fragment ions, made efficient chromatographic separation necessary. The analysis method provides valid accuracy (<9%; RSD%), precision (<8%; RSD%), linearity (<1.2 nM–1 μM; R2 > 0.999), limit of quantitation (<3.6 nM), retention repeatability (<1.2%; RSD%), selectivity, as well as analyte and column stabilities over a wide concentration range.

    Keywords
    Online, solid phase extraction, liquid chromatography, mass spectrometry, ximelagatran, metabolites, pig liver
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-88170 (URN)10.1016/j.jchromb.2008.12.017 (DOI)000262877500026 ()19117807 (PubMedID)
    Available from: 2009-01-22 Created: 2009-01-22 Last updated: 2022-01-28Bibliographically approved
    3. Hepatic disposition of ximelagatran and its metabolites in pig; prediction of the impact of membrane transporters through a simple disposition model
    Open this publication in new window or tab >>Hepatic disposition of ximelagatran and its metabolites in pig; prediction of the impact of membrane transporters through a simple disposition model
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    2010 (English)In: Pharmaceutical research, ISSN 0724-8741, E-ISSN 1573-904X, Vol. 27, no 4, p. 597-607Article in journal (Refereed) Published
    Abstract [en]

    Purpose: The double prodrug ximelagatran is bioconverted, via the intermediates ethylmelagatran and N-hydroxymelagatran, to the direct thrombin inhibitor melagatran. The aims of this study were 1) to investigate the hepatic metabolism and disposition of ximelagatran and the intermediates in pig; and 2) to test a simple in vitro methodology for quantitative investigations of membrane transporters impact on the disposition of metabolized drugs. Methods: Porcine S1 (supernatant fraction obtained by centrifuging at 1000g for 10 min) liver fractions and hepatocytes were incubated in absence and presence of known membrane transporter inhibitors. The in vitro kinetics and disposition were determined by simultaneously fitting of the disappearance of ximelagatran and appearance of ethylmelagatran, N-hydroxymelagatran and melagatran. Results: In S1 liver fractions, the metabolism was significant inhibited by co-incubation of verapamil and ketoconazole but not by erythromycin, quinine and quinidine. The disposition of ximelagatran and the intermediate metabolites in hepatocytes were influenced, to various degrees, by carrier-mediated distribution processes. Conclusion: This work demonstrates that it is possible to obtain profound information of the general mechanisms important in the drug liver disposition with the combination of common in vitro systems and the simple disposition model proposed in this study.

    Keywords
    melagatran, prodrug, hepatic disposition, kinetic modeling, hepatocytes
    National Category
    Pharmacology and Toxicology
    Research subject
    Drug Metabolism
    Identifiers
    urn:nbn:se:uu:diva-110319 (URN)10.1007/s11095-009-0016-y (DOI)000275556000007 ()20140637 (PubMedID)
    Available from: 2009-11-10 Created: 2009-11-10 Last updated: 2022-01-28Bibliographically approved
    4. Exploring liquid chromatography-mass spectrometry fingerprints of urine samples from patients with prostate or urinary bladder cancer
    Open this publication in new window or tab >>Exploring liquid chromatography-mass spectrometry fingerprints of urine samples from patients with prostate or urinary bladder cancer
    2011 (English)In: Chemometrics and Intelligent Laboratory Systems, ISSN 0169-7439, E-ISSN 1873-3239, Vol. 108, no 1, p. 33-48Article in journal (Refereed) Published
    Abstract [en]

    Data processing and analysis have become true rate and success limiting factors for molecular research where a large number of samples of high complexity are included in the data set. In general rather complicated methodologies are needed for the combination and comparison of information as obtained from selected analytical platforms. Although commercial as well as freely accessible software for high-throughput data processing are available for most platforms, tailored in-house solutions for data management and analysis can provide the versatility and transparency eligible for e.g. method development and pilot studies. This paper describes a procedure for exploring metabolic fingerprints in urine samples from prostate and bladder cancer patients with a set of in-house developed Matlab tools. In spite of the immense amount of data produced by the LC-MS platform, in this study more than 1010 data points, it is shown that the data processing tasks can be handled with reasonable computer resources. The preprocessing steps include baseline subtraction and noise reduction, followed by an initial time alignment. In the data analysis the fingerprints are treated as 2-D images, i.e. pixel by pixel, in contrast to the more common list-based approach after peak or feature detection. Although the latter approach greatly reduces the data complexity, it also involves a critical step that may obscure essential information due to undetected or misaligned peaks. The effects of remaining time shifts after the initial alignment are reduced by a binning and [‘]blurring’ procedure prior to the comparative multivariate and univariate data analyses. Other factors than cancer assignment were taken into account by ANOVA applied to the PCA scores as well as to the individual variables (pixels). It was found that the analytical day-to-day variations in our study had a large confounding effect on the cancer related differences, which emphasizes the role of proper normalization and/or experimental design. While PCA could not establish significant cancer related patterns, the pixel-wise univariate analysis could provide a list of about a hundred [‘]hotspots’ indicating possible biomarkers. This was also the limited goal for this study, with focus on the exploration of a really huge and complex data set. True biomarker identification, however, needs thorough validation and verification in separate patient sets.

    Keywords
    Urine profile, LC MS, Metabolic fingerprinting
    National Category
    Analytical Chemistry
    Research subject
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-110321 (URN)10.1016/j.chemolab.2011.03.008 (DOI)000293430300005 ()
    Available from: 2009-11-10 Created: 2009-11-10 Last updated: 2017-12-12Bibliographically approved
    5. Quantitative aspects of analyzing small molecules - monitoring singly or doubly charged ions?: A case study of ximelagatran.
    Open this publication in new window or tab >>Quantitative aspects of analyzing small molecules - monitoring singly or doubly charged ions?: A case study of ximelagatran.
    2010 (English)In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 24, no 4, p. 429-435Article in journal (Refereed) Published
    Abstract [en]

    Precision, reproducibility and lower limit of quantitation (LLOQ) are important characteristics of a quantitative method. We have investigated these properties for Ximelagatran (Xi), which has a high tendency to form doubly charged ions in electrospray ionization (ESI), by studying the percentage of doubly charged species formed when varying the formic acid (FA) concentration, analyte concentration, amount of organic modifier and flow rate. It was found that the percentage of [Xi + 2H]2+ can be controlled to be more than 90% or less than 10% by varying the amount of FA present, and that the change between these values is dramatic. Furthermore, the percentage of [Xi + 2H]2+ formed decreases with increased analyte concentration and increased flow rate. No apparent relationship with the amount of organic modifier was found. The results have the implication that, by carefully controlling the selected parameters, the LLOQ, precision and reproducibility can be improved. We have compared the fragmentation of the singly and doubly charged species and concluded that the [Xi + 2H]2+ ion is more inclined to undergo fragmentation than [Xi + H]+. As a consequence, unusual instrumental settings had to be used for the experiments. The fragmentation patterns are to a great extent similar, but the doubly charged species is more inclined to generate low-mass product ions.

    Keywords
    Charge state, ximelagatran, quantitation, ESI
    National Category
    Chemical Sciences
    Research subject
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-110320 (URN)10.1002/rcm.4414 (DOI)000274585000006 ()20069691 (PubMedID)
    Available from: 2009-11-10 Created: 2009-11-10 Last updated: 2022-01-28Bibliographically approved
    Download full text (pdf)
    FULLTEXT01
  • 15.
    Allard, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Bäckström, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Danielsson, Rolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Sjöberg, Per J.R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Comparing capillary electrophoresis: mass spectrometry fingerprints of urine samples obtained after intake of coffee, tea, or water.2008In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 80, no 23, p. 8946-8955Article in journal (Refereed)
    Abstract [en]

    Metabolomic fingerprinting is a growing strategy for characterizing complex biological samples without detailed prior knowledge about the metabolic system. A two-way analysis system with liquid separation and mass spectrometric detection provides detail-rich data suitable for such fingerprints. As a model study, human urine samples, obtained after intake of coffee, tea, or water, were analyzed with capillary electrophoresis electrospray ionization time-of-flight mass spectrometry (CE−ESI-TOF-MS). In-house-developed software (in Matlab) was utilized to manage and explore the large amount of data acquired (230 CE−MS runs, each with 50−100 million nonzero data points). After baseline and noise reduction, followed by suitable binning in time and m/z, the data sets comprised 9 and 14 million data points in negative and positive ESI mode, respectively. Finally, a signal threshold was applied, further reducing the number to about 100 000 data points per data set. A set of interactive exploratory tools, utilizing principal component analysis (PCA) and analysis of variance (ANOVA) results based on a general linear model, facilitated visual interpretation with score plots (for group assessment) and differential fingerprints (for “hot spot” detection). In the model study highly significant differences due to beverage intake were obtained among the 10 first principal components (p < 10−6 for two of the components in both ESI modes). Especially, the contrasts between “coffee” and “tea or water” indicated several “hot spots” with highly elevated intensities (e.g., for uncharged masses 93, 94, 109, 119, 123, 132, 148, 169, 178, 187, 190, and 193) suitable for further analysis, for example, with tandem MS.

  • 16. Allison, Timothy M.
    et al.
    Barran, Perdita
    Benesch, Justin L. P.
    Cianférani, Sarah
    Degiacomi, Matteo T.
    Gabelica, Valérie
    Grandori, Rita
    Marklund, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Menneteau, Thomas
    Migas, Lukasz G.
    Politis, Argyris
    Sharon, Michal
    Sobott, Frank
    Thalassinos, Konstantinos
    Software Requirements for the Analysis and Interpretation of Native Ion Mobility Mass Spectrometry Data2020In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 92, no 16, p. 10881-10890Article in journal (Refereed)
    Abstract [en]

    The past few years have seen a dramatic increase in applications of native mass and ion mobility spectrometry, especially for the study of proteins and protein complexes. This increase has been catalyzed by the availability of commercial instrumentation capable of carrying out such analyses. As in most fields, however, the software to process the data generated from new instrumentation lags behind. Recently, a number of research groups have started addressing this by developing software, but further improvements are still required in order to realize the full potential of the data sets generated. In this perspective, we describe practical aspects as well as challenges in processing native mass spectrometry (MS) and ion mobility-MS data sets and provide a brief overview of currently available tools. We then set out our vision of future developments that would bring the community together and lead to the development of a common platform to expedite future computational developments, provide standardized processing approaches, and serve as a location for the deposition of data for this emerging field. This perspective has been written by members of the European Cooperation in Science and Technology Action on Native MS and Related Methods for Structural Biology (EU COST Action BM1403) as an introduction to the software tools available in this area. It is intended to serve as an overview for newcomers and to stimulate discussions in the community on further developments in this field, rather than being an in-depth review. Our complementary perspective (http://dx.doi.org/10.1021/acs.analchem.9b05791) focuses on computational approaches used in this field.

  • 17. Allison, Timothy M.
    et al.
    Barran, Perdita
    Cianférani, Sarah
    Degiacomi, Matteo T.
    Gabelica, Valérie
    Grandori, Rita
    Marklund, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Menneteau, Thomas
    Migas, Lukasz G.
    Politis, Argyris
    Sharon, Michal
    Sobott, Frank
    Thalassinos, Konstantinos
    Benesch, Justin L. P.
    Computational Strategies and Challenges for Using Native Ion Mobility Mass Spectrometry in Biophysics and Structural Biology2020In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 92, no 16, p. 10872-10880Article in journal (Refereed)
    Abstract [en]

    Native mass spectrometry (MS) allows the interrogation of structural aspects of macromolecules in the gas phase, under the premise of having initially maintained their solution-phase noncovalent interactions intact. In the more than 25 years since the first reports, the utility of native MS has become well established in the structural biology community. The experimental and technological advances during this time have been rapid, resulting in dramatic increases in sensitivity, mass range, resolution, and complexity of possible experiments. As experimental methods have improved, there have been accompanying developments in computational approaches for analyzing and exploiting the profusion of MS data in a structural and biophysical context. In this perspective, we consider the computational strategies currently being employed by the community, aspects of best practice, and the challenges that remain to be addressed. Our perspective is based on discussions within the European Cooperation in Science and Technology Action on Native Mass Spectrometry and Related Methods for Structural Biology (EU COST Action BM1403), which involved participants from across Europe and North America. It is intended not as an in-depth review but instead to provide an accessible introduction to and overview of the topic—to inform newcomers to the field and stimulate discussions in the community about addressing existing challenges. Our complementary perspective (http://dx.doi.org/10.1021/acs.analchem.9b05792) focuses on software tools available to help researchers tackle some of the challenges enumerated here.

  • 18.
    Allison, Timothy M.
    et al.
    Biomolecular Interaction Centre, School of Physical and Chemical Sciences, University of Canterbury, Christchurch, New Zealand.
    Degiacomi, Matteo T.
    Department of Physics, Durham University, Durham, UK.
    Marklund, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Biochemistry.
    Jovine, Luca
    Department of Biosciences and Nutrition, Karolinska Institutet, Huddinge, Sweden.
    Elofsson, Arne
    Science for Life Laboratory and Department of Biochemistry and Biophysics, Stockholm University, Solna, Sweden.
    Benesch, Justin L. P.
    Department of Chemistry, University of Oxford, Oxford, UK.
    Landreh, Michael
    Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet – Biomedicum, Stockholm, Sweden.
    Complementing machine learning‐based structure predictions with native mass spectrometry2022In: Protein Science, ISSN 0961-8368, E-ISSN 1469-896X, Vol. 31, no 6, article id e4333Article in journal (Refereed)
    Abstract [en]

    The advent of machine learning-based structure prediction algorithms such as AlphaFold2 (AF2) and RoseTTa Fold have moved the generation of accurate structural models for the entire cellular protein machinery into the reach of the scientific community. However, structure predictions of protein complexes are based on user-provided input and may require experimental validation. Mass spectrometry (MS) is a versatile, time-effective tool that provides information on post-translational modifications, ligand interactions, conformational changes, and higher-order oligomerization. Using three protein systems, we show that native MS experiments can uncover structural features of ligand interactions, homology models, and point mutations that are undetectable by AF2 alone. We conclude that machine learning can be complemented with MS to yield more accurate structural models on a small and large scale.

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    fulltext
  • 19.
    Amini, Ahmad
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Analysis of Caffeine in Dietary Products by Multiple Injection Capillary Electrophoresis2012In: Caffeine: Chemistry, Analysis, Function and Effects / [ed] Victor R Preedy, London: Royal Society of Chemistry, 2012, p. 154-178Chapter in book (Refereed)
  • 20.
    Amini, Ahmad
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Double-injection capillary electrophoresis for the identification of analytes2014In: Electrophoresis, ISSN 0173-0835, E-ISSN 1522-2683, Vol. 35, no 20, p. 2915-2921Article in journal (Refereed)
    Abstract [en]

    This paper presents a new approach for identifying analytes by CE. The compound to be identified is analyzed together with the corresponding reference standard during a double injection capillary electrophoretic run. The inter-plug distance is regulated by applying an electrical field over the capillary for a predetermined time period (tPE). The migration time of an analyte being exposed to the partial electrophoresis was calculated from the partial migration time (tmig(p)) as described in this paper. The identification is based on the closeness of agreement between the calculated migration time (tmig(c)) and observed migration time (tmig) of the reference standard. The validity of the derived equations was checked by analyzing several substances such as caffeine, melamine, acetyl salicylic acid, paracetamol, ibuprofen, metoprolol, naproxen, somatropin, several insulin analogs, as well as different pharmaceutical and natural products. The migration time ratios for the identified solutes varied between 0.996 and 1.006 (i.e., 1.001 ± 0.005), indicating good agreement between the observed and calculated migration times.

  • 21.
    Amini, Ahmad
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Identification of Ɛ-Caprolactam and Melamine in Polyvinyl- Pyrrolidone Powder by Double Injection Micellar Elektrokinetic Chromatography2015In: Pharmaceutica analytica acta, ISSN 2153-2435, Vol. 6, no 11, article id 1000442Article in journal (Refereed)
    Abstract [en]

    A double-injection micellar electrokinetic chromatography (DIMEKC) method for the identification of Ɛ- caprolactam andmelamine deliberately added to povidone (polyvinylpyrrolidone) products has been developed. The separations were performedin 89 mM phosphate buffer (pH 7.4) containing 52 mM sodium dodecyl sulfate (SDS) in fused silica capillaries with UV absorptiondetection at 200 nm. The identification relied on the agreement between the calculated migration time (t mig(c) ) of the analytes andthe migration time (t mig ) of their corresponding reference standards being analysed simultaneously within a double injection run.The migration time of the analytes was calculated from the partial migration times (t mig(p) ) as described in this paper. The migrationtime ratios (t mig(c) / t mig ) varied

  • 22.
    Amini, Ahmad
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Identification of ε-caprolactam, melamine and urea in polyvinylpyrrolidone powders by micellar electrokinetic chromatography2014In: Journal of Pharmaceutical and Biomedical Analysis, ISSN 0731-7085, E-ISSN 1873-264X, Vol. 91, p. 12-16Article in journal (Refereed)
    Abstract [en]

    A sodium dodecyl sulfate micellar electrokinetic chromatography (SDS-MEKC) method for the simultaneous separation and identification of ɛ-caprolactam, melamine and urea deliberately added to polyvinylpyrrolidone (povidone) products has been developed. All samples to be analyzed contained paracetamol as an internal marker (IM). The optimized separations were performed in 50 mM phosphate buffer (pH 7.0) containing 2% (w/v) sodium dodecyl sulfate (SDS) in fused silica capillaries with UV absorption detection at 200 nm. The method was validated with respect to repeatability and intermediate precision, selectivity and robustness with satisfactory results. The relative migration times (RMT) were found to be between 0.03% and 0.13% for intra-day precision and between 0.50% and 0.60% for inter-day precision in four days. The detection limits were determined to be 1.3 (11.5 μM), 0.4 (3.5 μM) and 41 μg/ml (0.4 mM) for ɛ-caprolactam, melamine and urea, respectively.

  • 23.
    Amini, Ahmad
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Rundlöf, Torgny
    Rönnquist, Kerstin
    Tydén, Monica
    Turunen, Taina
    Korhola, Paula
    Anette, Perolari
    A protocol for the quality assessment of illegally distributed human growth hormones with respect to identity, purity, endotoxin level and microorganism content2015In: Analytical Methods, ISSN 1759-9660, E-ISSN 1759-9679, Vol. 7, no 20, p. 8857-8864Article in journal (Refereed)
    Abstract [en]

    Different methods based on MALDI-TOF-MS and double injection capillary zone electrophoresis (DICZE) were used for the identification and purity determination of somatropin in illegally distributed products. During the past few years, more than 200 products suspected to contain somatropin have been analysed. Some of the samples were also subjected to control microorganisms and endotoxins. The identification of somatropin was carried out by peptide mapping using trypsin as the proteolytic enzyme. A double chain peptide cross-linked via a disulfide bond was used as the signature peptide. Capillary electrophoresis in double injection mode was applied to both identification and purity determination of the samples. The identification was based on the comparison between the observed migration time of the reference standard and the calculated migration time of the analyte, being present in the second injection plug. The DICZE provides electrophoretic fingerprints of intact somatropin and the related proteins which facilitate the identification. In addition, some of these samples revealed the presence of microorganisms as well as a high level of endotoxins. Taken together, the doubtful quality of the analysed samples and the microbiological findings represent a serious threat for the consumers and public health.

  • 24.
    Amirkhani, A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry.
    Heldin, E.
    Markides, K.E.
    Bergquist, J.
    Quantitation of tryptophan, kynurenine and kynurenic acid in human plasma by capillary liquid chromatography - electrospray ionization tandem mass spectrometry2002In: J. of Chromatography B, no 780, p. 381-387Article in journal (Refereed)
  • 25.
    Amirkhani, Ardeshir
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry, Analytical Chemistry.
    Development of Techniques and Methods for the Quantitative Analysis of Endogenous Substances by Microcolumn Liquid Chromatography Coupled to Mass Spectrometry2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Liquid chromatography-mass spectrometry (LC-MS) is a powerful technique for the analysis of endogenous compounds. The introduction of electrospray ionization (ESI) as an interface between LC and MS has contributed strongly to a trend towards miniaturization of LC, due to the possibility to perform ESI at low flow rates. In this thesis, several aspects regarding the design of miniaturized LC systems and electrospray emitters were investigated. In addition miniaturized LC-ESI-MS have been used for the qualitative and quantitative analysis of endogenous polar compounds, peptides and protein digests.

    The performance of miniaturized LC-MS was compared using different electrospray emitter configurations. The results indicated that the efficiency of the LC system is rather independent of the configuration of the emitter.

    The lifetime of gold-coated fused silica electrospray emitters based on vapor deposited adhesion layers of titanium were investigated. The long lifetime of the emitter facilitates the use in LC-MS experiments, exemplified LC-MS by analysis of neuropeptides.

    The ESI voltage is shown to interfere with liquid chromatographic separations performed in packed porous graphitic carbon capillary column. This interference is ascribed to the presence of an electric field over the conductive column in absence of a ground point between the column and the ESI emitter.

    The solid supported enhanced microdialysis for analysis of neuropeptides were compared with conventional microdialysis. The difference between the two methodologies were evaluated by LC-MS analysis of the microdialysates. The solid supported method gave in general higher relative recoveries.

    Finally, a method of standard addition was developed to determine total level of tryptophan and two of its metabolites in human plasma by capillary LC-ESI tandem mass spectrometry. The method was applied in a clinical study of multiple scleroses patients treated with cytokines (IFN Beta 1a, 1b). The results show that the intervention effects the tryptophan metabolism.

    List of papers
    1. Comparison between different sheathless electrospray emitter configurations regarding the performance of nanoscale liquid chromatography time-of-flight mass spectrometry analysis
    Open this publication in new window or tab >>Comparison between different sheathless electrospray emitter configurations regarding the performance of nanoscale liquid chromatography time-of-flight mass spectrometry analysis
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    2004 (English)In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1033, no 2, p. 257-266Article in journal (Refereed) Published
    Abstract [en]

    Four different sheathless electrospray ionization (ESI) configurations were investigated for a nano liquid chromatography (LC) system. The studied configurations were: a column with an integrated emitter, with the ESI potential applied before or after the column, and a column with separate emitter, with the ESI voltage applied at a union before the emitter or at the emitter tip. The results indicates that the efficiency of the LC system is rather independent of the configuration when using 95 μm i.d. columns, acetic mobile phase and standard peptides as a sample. Introduction of post column dead volume seems not to be a critical issue at least with flow rates down to 600 nl/min.

    Keywords
    Electrospray ionization, Band broadening, Principal component analysis, Instrumentation, Peptides
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-91889 (URN)10.1016/j.chroma.2004.01.063 (DOI)
    Available from: 2004-05-25 Created: 2004-05-25 Last updated: 2017-12-14Bibliographically approved
    2. Gold-coated fused-silica sheathless electrospray emitters based on vapor-deposited titanium adhesion layers
    Open this publication in new window or tab >>Gold-coated fused-silica sheathless electrospray emitters based on vapor-deposited titanium adhesion layers
    Show others...
    2003 In: Rapid Communication Mass Spectrometry, Vol. 17, no 14, p. 1535-1540Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-91337 (URN)
    Available from: 2004-01-30 Created: 2004-01-30Bibliographically approved
    3. Interference of the electrospray voltage on chromatographic separations using porous graphitic carbon columns
    Open this publication in new window or tab >>Interference of the electrospray voltage on chromatographic separations using porous graphitic carbon columns
    Show others...
    2004 (English)In: Journal of Mass Spectrometry, ISSN 1076-5174, E-ISSN 1096-9888, Vol. 39, no 2, p. 216-222Article in journal (Refereed) Published
    Abstract [en]

    The electrospray ionization (ESI) voltage is shown to interfere with liquid chromatographic separations performed with packed porous graphitic carbon (PGC) capillary columns. This interference is ascribed to the presence of an electric field over the conductive column in the absence of an earth point between the column and the ESI emitter. The current evolved alters the chromatographic behavior of the catecholamine metabolite 3-O-methyl-DOPA significantly, as both peak splitting and a dramatic decrease in the retention time were observed. Furthermore, the response from the mass spectrometer was decreased by 33% at the same time. A related compound, tyrosine, exhibited decreased retention times but no peak splitting, whereas no shifts in the retention times (or peak splitting) were seen for the less retained dopamine and noradrenaline. When the current through the PGC column was eliminated by the use of an earth point between the column and the ESI emitter, the chromatographic behavior of the column was found to return slowly to normal after hours of equilibration with 60 : 40 (v/v) methanol-ammonium formate buffer of pH 2.9. The behavior of the PGC column with and without the earth point was found to be highly reproducible during a period of 1 month. We propose that the effect of the ESI voltage on the chromatographic behavior of the PGC column is due to associated redox reactions affecting both the PGC particles and the analytes. It is concluded that (for analytical reasons), care should be taken to ensure that no current is flowing through the chromatographic system when interfacing PGC columns, and conducting parts in general, to ESI mass spectrometry.

    Keywords
    catecholamine, dopamine, electrochemistry, porous graphitic carbon, electrospray, mass spectrometry, liquid chromatography
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-91888 (URN)10.1002/jms.589 (DOI)
    Available from: 2004-05-25 Created: 2004-05-25 Last updated: 2017-12-14Bibliographically approved
    4. A feasibility study of solid supported enhanced microdialysis
    Open this publication in new window or tab >>A feasibility study of solid supported enhanced microdialysis
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    2004 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 76, no 6, p. 1678-1682Article in journal (Refereed) Published
    Abstract [en]

    For the first time, a solid supported enhanced microdialysis methodology for analysis of neuropeptides is described. The microdialysis samples were, in this study, subsequently collected in fractions, dissolved from the solid particles, dried, and resolved in a formic acid buffer in order to make them suitable for capillary liquid chromatography-mass spectrometry. Different microdialysis flow profiles were evaluated where air-gapped continuous flow was considered most suitable for the solid supported microdialysis mode. Six endogenous neuropeptides were initially used to investigate the feasibility of this enhanced microdialysis methodology. The improved relative recovery obtained from the solid supported enhanced microdialysis was varying from no effect to 10 times higher as compared to ordinary microdialysis. The most efficient enrichment was obtained for luteinizing hormone releasing hormone, which was the largest but also the most hydrophilic of the peptides. In contrast, no significant difference in recovery was observed for Leu-enkephalin being the smallest and the most hydrophobic peptide tested. These results indicate an increased flux and selective uptake of hydrophilic peptides across the membrane and enrichment on the particles in solid supported microdialysis.

    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-93181 (URN)10.1021/ac035305l (DOI)15018567 (PubMedID)
    Available from: 2005-05-10 Created: 2005-05-10 Last updated: 2017-12-14Bibliographically approved
    5. Quantitation of tryptophan, kynurenine and kynurenic acid in human plasma by capillary liquid chromatography - electrospray
    Open this publication in new window or tab >>Quantitation of tryptophan, kynurenine and kynurenic acid in human plasma by capillary liquid chromatography - electrospray
    2002 In: Journal of Chromatography B, Vol. 780, no 2, p. 381-387Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-91340 (URN)
    Available from: 2004-01-30 Created: 2004-01-30 Last updated: 2011-03-21
    6. Beta-interferon effects the tryptophan metabolism in the plasma of multiple sclerosis patients
    Open this publication in new window or tab >>Beta-interferon effects the tryptophan metabolism in the plasma of multiple sclerosis patients
    Show others...
    Manuscript (Other academic)
    Identifiers
    urn:nbn:se:uu:diva-91341 (URN)
    Available from: 2004-01-30 Created: 2004-01-30 Last updated: 2011-03-21
    Download full text (pdf)
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  • 26.
    Andaloussi, Mounir
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Lindh, Jonas
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry. ORGFARM.
    Sävmarker, Jonas
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Sjöberg, Per J.R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Larhed, Mats
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Organic Pharmaceutical Chemistry.
    Microwave-promoted palladium(II)-catalyzed C-P bond formation by using arylboronic acids or aryltrifluoroborates.2009In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 15, no 47, p. 13069-13074Article in journal (Refereed)
    Abstract [en]

    The first Pd-II-catalyzed P arylation has been performed by using palladium acetate, the rigid bidentate ligand dmphen (dmphen=2,9-dimethyl-1,10-phenanthroline), and without the addition of base or acid. Couplings of arylboronic acids or aryl trifluoroborates with H-phosphonate dialkyl esters were conducted in 30 min with controlled microwave (MW) heating under non-inert conditions. Aryl phosphites were also synthesized at room temperature with atmospheric air as the sole reoxidant. The arylated phosphonates were isolated in 44-90% yields. The excellent chemoselectivity of the method was illustrated in the synthesis of a Mycobacterium tuberculosis glutamine synthetase (MTB-GS) inhibitor. Online ESIMS was used to detect cationic palladium species in ongoing reactions directly, and a catalytic cycle has been proposed based on these results.

  • 27.
    Anderson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Development of Electroacoustic Sensors for Biomolecular Interaction Analysis2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Biomolecular interaction analysis to determine the kinetics and affinity between interacting partners is important for the fundamental understanding of biology, as well as for the development of new pharmaceutical substances. A quartz crystal microbalance instrument suitable for kinetics and affinity analyses of interaction events was developed. The functionality of the sensor system was demonstrated by development of an assay for relative affinity determination of lectin-carbohydrate interactions.

    Sensor surfaces allowing for effective immobilization of one interacting partner is a key functionality of a biosensor. Here, three different surfaces and immobilization methods were studied. First, optimized preparation conditions for sensor surfaces based on carboxyl-terminated self assembled monolayers were developed and were demonstrated to provide highly functional biosensor surfaces with low non-specific binding. Second, a method allowing for immobilization of very acidic biomolecules based on the use of an electric field was developed and evaluated. The electric field made it possible to immobilize the highly acidic C-peptide on a carboxylated surface. Third, a method for antibody immobilization on a carboxyl surface was optimized and the influence of immobilization pH on the immobilization level and antigen binding capacity was thoroughly assessed. The method showed high reproducibility for a set of antibodies and allowed for antibody immobilization also at low pH.

    Three broadly different strategies to increase the sensitivity of electroacoustic sensors were explored. A QCM sensor with small resonator electrodes and reduced flow cell dimensions was demonstrated to improve the mass transport rate to the sensor surface. The use of polymers on QCM sensor surfaces to enhance the sensor response was shown to increase the response of an antibody-antigen model system more than ten-fold. Moreover, the application of high frequency thin film bulk acoustic resonators for biosensing was evaluated with respect to sensing range from the surface. The linear detection range of the thin film resonator was determined to be more than sufficient for biosensor applications involving, for instance, antibody-antigen interactions. Finally, a setup for combined frequency and resistance measurements was developed and was found to provide time resolved data suitable for kinetics determination.

    List of papers
    1. Study of real-time lectin-carbohydrate interactions on the surface of a quartz crystal microbalance
    Open this publication in new window or tab >>Study of real-time lectin-carbohydrate interactions on the surface of a quartz crystal microbalance
    2005 (English)In: Biosensors & Bioelectronics, Vol. 21, p. 60-66Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-26504 (URN)
    Available from: 2007-02-19 Created: 2007-02-19 Last updated: 2011-01-12
    2. Esterification of Self-Assembled Carboxylic-Acid-Terminated Thiol Monolayers in Acid Environment: A Time-Dependent Study
    Open this publication in new window or tab >>Esterification of Self-Assembled Carboxylic-Acid-Terminated Thiol Monolayers in Acid Environment: A Time-Dependent Study
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    2010 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 26, no 2, p. 821-829Article in journal (Refereed) Published
    Abstract [en]

    This contribution reports on the influence of acids oil the quality of carboxylic-acid-terminated self-assembled monolayers (SAMs) on gold prepared from ethanolic solution of HS-(CH2)(15)-COOH and HS-(CH2)(11)CONH-(EG)(6)CH2-COOH. Null ellipsometry, contact angle goniometry, and infrared reflection-absorption spectroscopy are used to monitor the physical and chemical changes occurring within the SAMs upon acid post treatment; after incubation with acids present in the solution: and after incubation in aged acid containing solutions. The presence of acid has a positive effect oil the crystallinity, packing, and orientation Of the Supporting alkyl and ethylene glycol Subunits of the SAM. Our Studies also confirm previous findings stating that the carboxylic groups are rapidly converted into ethyl ester groups in the presence of hydrochloric acid in the incubation solution. It is also evident that the conversion occurs in the presence of the weaker acid, acetic acid, although at a much slower rate than that for hydrochloric acid. This is a new observation that has not been reported on before. The physical and chemical characterization is also complemented with a functional bioaffinity study. The functional evaluation revealed that the present model system was surprisingly insensitive to the degree of esterification of the carboxylic acid groups, but that 4 weeks of storage of the two investigated thiols in hydrochloric acid containing ethanol resulted in SAMs that were completely inactive with respect to immobilization and subsequent binding of the antigen. It was encouraging to note that the nonspecific binding of both antigen and antibody was extremely low oil the two SAMs, regardless of the relative amount of ethyl esters on the surface.

    National Category
    Engineering and Technology Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-137945 (URN)10.1021/la902255j (DOI)000273403400029 ()
    Available from: 2010-12-16 Created: 2010-12-16 Last updated: 2022-01-28Bibliographically approved
    3. Electroimmobilization of proinsulin C-peptide to a quartz crystal microbalance sensor chip for protein affinity purification
    Open this publication in new window or tab >>Electroimmobilization of proinsulin C-peptide to a quartz crystal microbalance sensor chip for protein affinity purification
    Show others...
    2005 (English)In: Anal Biochem, Vol. 341, no 1, p. 89-93Article in journal (Refereed) Published
    Identifiers
    urn:nbn:se:uu:diva-26506 (URN)
    Available from: 2007-02-19 Created: 2007-02-19 Last updated: 2011-01-12
    4. Optimizing immobilization on two-dimensional carboxyl surface: pH dependence of antibody orientation and antigen binding capacity
    Open this publication in new window or tab >>Optimizing immobilization on two-dimensional carboxyl surface: pH dependence of antibody orientation and antigen binding capacity
    Show others...
    2010 (English)In: Analytical Biochemistry, ISSN 0003-2697, E-ISSN 1096-0309, Vol. 398, no 2, p. 161-168Article in journal (Refereed) Published
    Abstract [en]

    The performance of immunosensors is highly dependent on the amount of immobilized antibodies and their remaining antigen binding capacity. In this work, a method for immobilization of antibodies on a two dimensional carboxyl surface has been optimized using quartz crystal microbalance biosensors. We have shown that successful immobilization is highly dependent on surface pKa, antibody pI and pH of immobilization buffer. By use of EDC/sulfo-NHS activation reagents, the effect of the intrinsic surface pKa is avoided and immobilization also at very low pH has been made possible which is of importance for immobilization of acidic proteins. Generic immobilization conditions were demonstrated on a panel of antibodies which resulted in an average coefficient of variation of 4% for the immobilization of these antibodies.

    Antigen binding capacity as a function of immobilization pH was studied. In most cases the antigen binding capacity followed the immobilization response. However, the antigen to antibody binding ratio differed between the antibodies investigated, and for one of the antibodies, the antigen binding capacity was significantly lower than expected from immobilization in a certain pH range. Tests with anti-Fc and anti-Fab antibodies on different antibody surfaces showed that the orientation of the antibodies on the surface had a profound effect on the antigen binding capacity of the immobilized antibodies.

    Keywords
    antibody, orientation, biosensor, immobilization, sensor surface, QCM
    National Category
    Other Industrial Biotechnology Analytical Chemistry
    Research subject
    Surface Biotechnology
    Identifiers
    urn:nbn:se:uu:diva-107233 (URN)10.1016/j.ab.2009.11.038 (DOI)000274615100003 ()19962366 (PubMedID)
    Available from: 2009-07-30 Created: 2009-07-30 Last updated: 2017-12-13Bibliographically approved
    5. Quartz crystal microbalance sensor design: I. Experimental study of sensor response and performance
    Open this publication in new window or tab >>Quartz crystal microbalance sensor design: I. Experimental study of sensor response and performance
    Show others...
    2007 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 123, no 1, p. 27-34Article in journal (Refereed) Published
    Abstract [en]

    This paper investigates a novel quartz crystal microbalance (QCM) biosensor with a small and rectangular flow cell along with a correspondingly shaped crystal electrode. The sensor was evaluated with impedance analysis and compared to standard circular sensor crystals and sensor crystals with small circular electrodes. Comparative QCM measurements on an antibody–antigen interaction system were carried out on the rectangular and standard circular sensor systems. Impedance analysis and subsequent data extraction of the three different sensor crystals showed that the smaller sensors had significantly higher Q-values in air, but that liquid load on the electrodes lowered the Q-values radically for all crystals. Under liquid load, Q-values for the standard circular and the rectangular sensors were similar whereas the Q-value for the small circular sensor was 50% higher. QCM experiments showed that the QCM system with rectangular crystal electrodes was fully functional in a liquid environment. The rectangular system showed higher and more rapid responses for series of antibody injections, albeit at a higher noise level than the standard system. The study elucidates a significant potential for improvement of sensor performance by optimising the sensor electrode size and shape together with the flow cell geometry.

    Keywords
    QCM, Biosensor, Sensitivity, Mass transport, Protein interactions
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-94271 (URN)10.1016/j.snb.2006.07.027 (DOI)000246171200006 ()
    Available from: 2006-04-07 Created: 2006-04-07 Last updated: 2017-12-14Bibliographically approved
    6. Quartz crystal microbalance biosensor design: II. Simulation of sample transport
    Open this publication in new window or tab >>Quartz crystal microbalance biosensor design: II. Simulation of sample transport
    2007 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 123, no 1, p. 21-26Article in journal (Refereed) Published
    Abstract [en]

    The influence of flow cell geometry on sample dispersion in a quartz crystal microbalance (QCM) biosensor system was investigated. A circular and a rectangular flow cell and corresponding sensor electrodes were studied experimentally and modelled using a coupled Navier-Stokes and convection-diffusion model. Finite element simulations showed that dispersion phenomena in a flow cell can be significantly reduced with the rectangular flow cell compared to a circular system. Experimental results from measurement of the time-dependent viscosity change of a model sample indicate that the sample delivery system has a predominant effect on the dispersion of the whole sensor system. Consequently, improvement of the sensor flow cell should be accompanied with improvement of the sample delivery system. With reference to kinetic studies of biological interactions, the current dispersion should have little effect on the results for studies of interaction pairs with relatively slow to normal binding rates such as antibody-antigen interactions. Incentive for further development of the flow cell and sample delivery system exists primarily for applications with high reaction rates such as for certain receptor ligand interactions.

     

    Keywords
    QCM, Simulation, FEM, Navier–Stokes, Convection and diffusion, Microfluidic
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-94272 (URN)10.1016/j.snb.2006.07.028 (DOI)000246171200005 ()
    Available from: 2006-04-07 Created: 2006-04-07 Last updated: 2022-01-28Bibliographically approved
    7. Surface-Confined Photopolymerization of pH-Responsive Acrylamide/Acrylate Brushes on Polymer Thin Films
    Open this publication in new window or tab >>Surface-Confined Photopolymerization of pH-Responsive Acrylamide/Acrylate Brushes on Polymer Thin Films
    Show others...
    2008 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, no 14, p. 7559-7564Article in journal (Refereed) Published
    Abstract [en]

    Dynamic acrylamide/acrylate polymeric brushes were synthesized at gold-plated quartz crystal surfaces. The crystals were initially coated with polystyrene-type thin films, derivatized with photolabile iniferter groups, and subsequently subjected to photoinitiated polymerization in acrylamide/acrylate monomer feeds. This surface-confined polymerizationmethod enabled direct photocontrol over the polymerization, as followed by increased frequency responses of the crystal oscillations in a quartz crystal microbalance (QCM). The produced polymer layers were also found to be highlysensitive to external acid/base stimuli. Large oscillation frequency shifts were detected when the brushes were exposedto buffer solutions of different pH. The dynamic behavior of the resulting polymeric brushes was evaluated, and theextent of expansion and contraction of the films was monitored by the QCM setup in situ in real time. The resultingresponses were rapid, and the effects were fully reversible. Low pH resulted in full contractions of the films, whereashigher pH yielded maximal expansion in order to minimize repulsion around the charged acrylate centers. The surfacesalso proved to be very robust because the responsiveness was reproducible over many cycles of repeated expansionand contraction. Using ellipsometry, copolymer layers were estimated to be ∼220 nm in a collapsed state and ∼340nm in the expanded state, effectively increasing the thickness of the film by 55%.

    Keywords
    Surface grafting, polymer brushes, hydrogels, sensor surfaces, transfer radical polymerization
    National Category
    Polymer Chemistry Physical Chemistry Engineering and Technology
    Research subject
    Surface Biotechnology
    Identifiers
    urn:nbn:se:uu:diva-107234 (URN)10.1021/la800700h (DOI)000257468300072 ()18563922 (PubMedID)
    Available from: 2009-07-30 Created: 2009-07-30 Last updated: 2017-12-13Bibliographically approved
    8. Signal Enhancement in Ligand-Receptor Interactions using Dynamic Polymers at Quartz Crystal Microbalance Surfaces
    Open this publication in new window or tab >>Signal Enhancement in Ligand-Receptor Interactions using Dynamic Polymers at Quartz Crystal Microbalance Surfaces
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    2016 (English)In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 141, no 13, p. 3993-3996Article in journal (Refereed) Published
    Abstract [en]

    The potential for signal amplification on QCM sensors by use of in situ polymerized poly(acrylic acid) brushes has been studied. A biotin derivative was immobilized on these surfaces and the interaction with anti-biotin Fabs was evaluated. Interaction data was found to be specific for the studied binding events, and the level of non-specific binding was shown to be low. The surface was proven to be suitable for regeneration, of importance for biomolecular interaction analysis and repetitive immunoassays.

    For comparison, the same interaction system was tested using commercial sensor surfaces with carboxylated self-assembled monolayers. The poly(acrylic acid) surface showed a dramatic increase in signal response with more than ten times the signal of the carboxylated self-assembled monolayer surface. Thus, the present study shows that polymers can be successfully applied to amplify responses on QCM sensors, valuable for studies of interactions between receptors and low molecular weight compounds.

    Keywords
    dynamic chemistry, quartz crystal microbalance, iniferter, photopolymerization, biosensor, interaction
    National Category
    Polymer Chemistry Engineering and Technology
    Research subject
    Surface Biotechnology
    Identifiers
    urn:nbn:se:uu:diva-107252 (URN)10.1039/c6an00735j (DOI)000378942300006 ()27196531 (PubMedID)
    External cooperation:
    Funder
    Swedish Research Council
    Available from: 2009-07-30 Created: 2009-07-30 Last updated: 2017-12-13Bibliographically approved
    9. On the applicability of high frequency acoustic shear mode biosensing in view of thickness limitations set by the film resonance
    Open this publication in new window or tab >>On the applicability of high frequency acoustic shear mode biosensing in view of thickness limitations set by the film resonance
    Show others...
    2009 (English)In: Biosensors & bioelectronics, ISSN 0956-5663, E-ISSN 1873-4235, Vol. 24, no 11, p. 3387-3390Article in journal (Refereed) Published
    Abstract [en]

    The IC-compatible thin film bulk acoustic resonator (FBAR) technology has made it possible to move the thickness excited shear mode sensing of biological layers into a new sensing regime using substantially higher operation frequencies than the conventionally used Quartz Crystal Microbalance (QCM). The limitations of the linear range set by the film resonance using viscoelastic protein films are here for the first time addressed specifically for FBARs operating at 700MHz up to 1.5GHz. Two types of protein multilayer sensing were employed; one utilizing alternating layers of Streptavidin and Biotinated BSA and the other using stepwise cross-linking of fibrinogen with EDC/NHS activation of its carboxyl groups. In both cases the number of protein layers within the linear regime is well above the number of protein layers usually used in biosensor applications, further verifying the applicability of the FBAR as a biosensor. Theoretical calculations are also presented using well established physical models to illustrate the expected behavior of the FBAR sensor, in view of both the frequency and the dissipation shifts.

    Keywords
    Shear mode electroacoustic sensing, Streptavidin–biotinated BSA, Fibrinogen, High frequency, Thin film bulk acoustic resonator (FBAR)
    National Category
    Engineering and Technology
    Research subject
    Electronics
    Identifiers
    urn:nbn:se:uu:diva-89406 (URN)10.1016/j.bios.2009.04.021 (DOI)000267577900035 ()
    Available from: 2009-02-12 Created: 2009-02-12 Last updated: 2018-06-26Bibliographically approved
    10. Systematic investigation of biomolecular interactions using combined frequency and motional resistance measurements
    Open this publication in new window or tab >>Systematic investigation of biomolecular interactions using combined frequency and motional resistance measurements
    Show others...
    2011 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 153, no 1, p. 135-144Article in journal (Refereed) Published
    Abstract [en]

    The resonance frequency of acoustic biosensors is today used as a label-free technique for detecting mass changes on sensor surfaces. In combination with an appropriate continuous flow system it has earlier been used for affinity and kinetic rate determination. Here, we assess the potential of a modified acoustic biosensor, monitoring also the real-time dissipation through the resistance of the sensor, to obtain additional kinetic information related to the structure and conformation of the molecules on the surface. Actual interaction studies, including an attempt to determine avidity, are presented along with thorough verification of the experimental setup utilizing true viscous load exposure together with protein and DNA immobilizations. True viscous loads show a linear relationship between resistance and frequency as expected. However, in the interaction studies between antibodies and proteins, as well as in the immobilization of DNA and proteins, higher surface concentrations of interacting molecules led to a decrease (i.e. deviation from the linear trend) in the differential resistance to frequency ratio. This is interpreted as increased surface rigidity at higher surface concentrations of immobilized molecules. Consequently, studies that aim at obtaining biological binding information, such as avidity, from real-time resistance and dissipation data should be conducted at low surface concentrations. In addition, the differential resistance to frequency relationship was found to be highly dependent on the rigidity of the preceding layer(s) of immobilized molecules. This dependence can be utilized to obtain a higher signal-to-noise ratio for resistance measurement by using low surface densities of immobilized interaction partners.

    Keywords
    biosensor, interaction analysis, QCM, dissipation, motional resistance, kinetics
    National Category
    Analytical Chemistry Other Industrial Biotechnology
    Research subject
    Analytical Chemistry; Engineering Science with specialization in Microsystems Technology; Engineering Science with specialization in Electronics
    Identifiers
    urn:nbn:se:uu:diva-107253 (URN)10.1016/j.snb.2010.10.019 (DOI)000289019300020 ()
    Available from: 2009-07-30 Created: 2009-07-30 Last updated: 2018-06-26Bibliographically approved
    Download full text (pdf)
    FULLTEXT01
  • 28.
    Anderson, Henrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Wingqvist, Gunilla
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Weissbach, Thomas
    Attana AB, Stockholm.
    Wallinder, Daniel
    Attana AB, Stockholm.
    Katardjiev, Ilia
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Electronics.
    Ingemarsson, Björn
    Attana AB, Stockholm.
    Systematic investigation of biomolecular interactions using combined frequency and motional resistance measurements2011In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 153, no 1, p. 135-144Article in journal (Refereed)
    Abstract [en]

    The resonance frequency of acoustic biosensors is today used as a label-free technique for detecting mass changes on sensor surfaces. In combination with an appropriate continuous flow system it has earlier been used for affinity and kinetic rate determination. Here, we assess the potential of a modified acoustic biosensor, monitoring also the real-time dissipation through the resistance of the sensor, to obtain additional kinetic information related to the structure and conformation of the molecules on the surface. Actual interaction studies, including an attempt to determine avidity, are presented along with thorough verification of the experimental setup utilizing true viscous load exposure together with protein and DNA immobilizations. True viscous loads show a linear relationship between resistance and frequency as expected. However, in the interaction studies between antibodies and proteins, as well as in the immobilization of DNA and proteins, higher surface concentrations of interacting molecules led to a decrease (i.e. deviation from the linear trend) in the differential resistance to frequency ratio. This is interpreted as increased surface rigidity at higher surface concentrations of immobilized molecules. Consequently, studies that aim at obtaining biological binding information, such as avidity, from real-time resistance and dissipation data should be conducted at low surface concentrations. In addition, the differential resistance to frequency relationship was found to be highly dependent on the rigidity of the preceding layer(s) of immobilized molecules. This dependence can be utilized to obtain a higher signal-to-noise ratio for resistance measurement by using low surface densities of immobilized interaction partners.

  • 29.
    Andersson, Annsofie
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Pharmaceutical knowledge retrieval through reasoning of ChEMBL RDF2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
  • 30.
    Andersson, Christoffer R.
    et al.
    Orebro Univ, Dept Neurol, Fac Med & Hlth, Orebro, Sweden..
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Theodorsson, Elvar
    Linkoping Univ, Dept Clin Chem, Linkoping, Sweden.;Linkoping Univ, Dept Clin & Expt Med, Linkoping, Sweden..
    Strom, Jakob O.
    Orebro Univ, Dept Neurol, Fac Med & Hlth, Orebro, Sweden.;Linkoping Univ, Dept Clin Chem, Linkoping, Sweden.;Linkoping Univ, Dept Clin & Expt Med, Linkoping, Sweden..
    Comparisons between commercial salivary testosterone enzyme-linked immunosorbent assay kits2017In: Scandinavian Journal of Clinical and Laboratory Investigation, ISSN 0036-5513, E-ISSN 1502-7686, Vol. 77, no 8, p. 582-586Article in journal (Refereed)
    Abstract [en]

    Introduction: Measuring testosterone concentrations is of interest both in clinical situations and for research, the latter expanding rapidly during recent years. An increased demand for convenient methods has prompted a number of companies to develop enzyme-linked immunosorbent assay (ELISA) kits to measure testosterone concentrations in saliva. However, the inter-comparability of kits from different manufacturers have yet to be determined. Aim of study: The aim of this study was to compare commercially available ELISA kits from four different manufacturers (Salimetrics, IBL, DRG and Demeditec). Methods: Saliva was collected from 50 participants (25 men and 25 women). Each sample was analysed by the four ELISA kits. Results: The correlations between the ELISA kits from Demeditec, DRG and Salimetrics were moderate to high with r-values >.77; however, proportional errors between the methods calls for caution. The ELISA kit from IBL malfunctioned and no results from this kit was obtained. Conclusions: Results from studies using the ELISA kits from Demeditec, DRG and Salimetrics are generally comparable; however, translation using the formulae presented in the current study could increase the accuracy of these comparisons.

  • 31.
    Andersson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Characterisation of Chromatography Media Aimed for Purification of Biomolecules2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Chromatography media (resins) are very important for and widely used by the biopharma industry in large scale production of biopharmaceuticals, e.g. monoclonal antibodies. Today there are several hundred biopharmaceuticals released globally on the healthcare market. This thesis discusses various strategies and methods for the characterisation of chemical and functional stability of chromatography media. In addition, various analytical techniques used in these areas were evaluated and applied. Further, more specific physical and chemical characterisation methods were evaluated and applied to explore different properties of various chromatography media.

    In Papers I-III, established methodologies for performing chemical and functional stability studies were used. Mainly agarose-based chromatography media were investigated. For fast screening of the chemical stability, the total organic carbon analysis technique was evaluated and applied. This technique that measures the carbon leakage from the chromatography media at different conditions, proved to be very suitable and robust. For detection and/or identification of leakage compounds responsible for or for part of the measured carbon leakage, different methods such as (high performance) liquid chromatography and gas chromatography mass spectrometry were used.

    In Papers IV-VII, different properties (i.e. functional performance, ligand content and surface chemistry) were evaluated for different agarose-based chromatography media. Standard chromatographic methods (ion exchange chromatography) and spectroscopic methods (e.g. Fourier transform infrared spectroscopy and time-of-flight secondary ion mass spectrometry) were evaluated and applied. Chemometric methods were used for efficient evaluation of data.

    Information of chemical, functional and leakage data of chromatography media are valuable and important for the biopharmaceutical companies to be able to fulfil the regulatory requirements of biopharmaceuticals. In addition, information of various chemical, functional and physical properties of chromatography media is likewise important during development and set up of new biopharmaceutical processes.

    List of papers
    1. The Influence of the Degree of Cross-linking, Type of Ligand and Support on the Chemical Stability of Chromatography Media Intended for protein Purification
    Open this publication in new window or tab >>The Influence of the Degree of Cross-linking, Type of Ligand and Support on the Chemical Stability of Chromatography Media Intended for protein Purification
    1998 (English)In: Process Biochemistry, ISSN 1359-5113, E-ISSN 1873-3298, Vol. 33, no 1, p. 47-55Article in journal (Refereed) Published
    Abstract [en]

    The release of organic compounds from different liquid chromatography media in static conditions has been analysed with a total organic carbon (TOC) analyser. TOC results show that chemical stability increases with the degree of cross-linking in agarose beaded chromatography media and thus extend the working pH-range of the media. Of the unsubstituted chromatography media investigated, Sepharose® 6B, Sepharose CL-6B, Sepharose 4 Fast Flow, Sepharose 6 Fast Flow and Sepharose High Performance, the latter was the most stable medium. Sepharose High Performance releases only about 0·06% of its total carbon content after 1 week in 0·01 m HCl. Agarose beads are more stable to basic conditions (pH 14) compared with acidic conditions (pH 2). From UV spectroscopic and gel filtration results it was found that all Sepharose media release low amounts of 5-(hydroxymethyl)-2-furaldehyde and agarose fragments in acidic conditions. To investigate the effect of different ligands on chemical stability Q Sepharose 6 Fast Flow, DEAE Sepharose 6 Fast Flow, SP Sepharose 6 Fast Flow, CM Sepharose 6 Fast Flow, Phenyl Sepharose 6 Fast Flow, Octyl Sepharose 4 Fast Flow media were also studied under static conditions. In basic conditions it was found that all these chromatography media release carbon compounds to a higher extent than the unsubstituted Sepharose support. In addition, Hofmann elimination of Q and DEAE groups contributes to the decrease in the carbon content of the corresponding anion exchangers. During exposure to acidic conditions (pH 2) the release of carbon compounds was lower than the release from the support to which the ligands were coupled. The exceptions are Octyl Sepharose 4 Fast Flow and SP Sepharose 6 Fast Flow. In the case of Octyl Sepharose 4 Fast Flow, the ligand did not seem to influence chemical stability, whereas the SP group increases the degradation of the Sepharose support. In the case of SP Sepharose 6 Fast Flow the stability in acidic conditions can be improved by increasing the ionic strength. Anion exchangers based on different support polymers (agarose-, polystyrene-, methacrylate- and polyvinyl-based matrixes) were studied under static conditions. Agarose-based anion exchanger was the most stable in basic conditions (pH 14). In acidic conditions (pH 2) the chemical stability was about the same for many different anion exchangers.

    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-234604 (URN)10.1016/S0032-9592(97)00068-X (DOI)
    Available from: 2014-10-23 Created: 2014-10-21 Last updated: 2017-12-05Bibliographically approved
    2. Characterization of the Chemical and Functional Stability of DEAE Sepharose Fast Flow
    Open this publication in new window or tab >>Characterization of the Chemical and Functional Stability of DEAE Sepharose Fast Flow
    1993 (English)In: Process Biochemistry, ISSN 1359-5113, E-ISSN 1873-3298, Vol. 28, no 4, p. 223-230Article in journal (Refereed) Published
    Abstract [en]

    The release of amines from the ion-exchange groups in DEAE Sepharose® Fast Flow has been studied under static and column conditions. The leakage compounds have been identified and quantified by gas chromatography—mass spectrometry. It was shown that the main leakage product under acidic (pH 1) and basic conditions (pH 14) was N,N,N′,N′-tetraethylethylenediamine. Three other amines were also identified, namely N,N,N′-triethylethylenediamine, diethylaminoethanol and diethylamine. The leakage of amines from DEAE Sepharose Fast Flow treated at pH 1 or 14 for 672 h at 40°C corresponds to a reduction of only 1% of the total ion-exchange capacity.

    The functional stability of DEAE Sepharose Fast Flow was also studied by separation of a protein mixture during repeated cleaning-in-place treatments with 0·10 m HCl or 1·0 m NaOH. The separation behaviour was unaltered after the gel had been treated for a total contact time of 672 h with 0·10 m HCl or 1·0 m NaOH.

    The clearance of ethanol from a DEAE Sepharose Fast Flow column stored in a 20% ethanol aqueous solution was also studied.

    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-234606 (URN)10.1016/0032-9592(93)80038-I (DOI)
    Available from: 2014-10-23 Created: 2014-10-21 Last updated: 2017-12-05Bibliographically approved
    3. A Systematic Approach to Screening Ion-Exchange Chromatography Media for Process Development
    Open this publication in new window or tab >>A Systematic Approach to Screening Ion-Exchange Chromatography Media for Process Development
    1996 (English)In: Biopharm, ISSN 1040-8304, Vol. 9, no 8, p. 42-45Article in journal (Refereed) Published
    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-234607 (URN)
    Available from: 2014-10-23 Created: 2014-10-21 Last updated: 2017-12-05Bibliographically approved
    4. Evaluation of Several Anion-exchange Media for process Separations Using a Variety of Proteins and Aromatic Acids
    Open this publication in new window or tab >>Evaluation of Several Anion-exchange Media for process Separations Using a Variety of Proteins and Aromatic Acids
    2001 (English)In: International Journal of Bio-Chromatography, ISSN 1068-0659, Vol. 6, p. 285-301Article in journal (Refereed) Published
    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-234609 (URN)
    Available from: 2014-10-23 Created: 2014-10-21 Last updated: 2015-02-03Bibliographically approved
    5. The multivariate use of vibrational spectroscopy for chemical characterisation of chromatography media
    Open this publication in new window or tab >>The multivariate use of vibrational spectroscopy for chemical characterisation of chromatography media
    2002 (English)In: Vibrational Spectroscopy, ISSN 0924-2031, E-ISSN 1873-3697, Vol. 29, p. 133-138Article in journal (Refereed) Published
    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-234611 (URN)
    Available from: 2014-10-23 Created: 2014-10-21 Last updated: 2017-12-05Bibliographically approved
    6. Surface Chemical Analysis of Carbohydrate Materials Used for Chromatography Media by Time-of-Flight Secondary Ion Mass Spectrometry
    Open this publication in new window or tab >>Surface Chemical Analysis of Carbohydrate Materials Used for Chromatography Media by Time-of-Flight Secondary Ion Mass Spectrometry
    2004 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 76, no 7, p. 1857-1864Article in journal (Refereed) Published
    Abstract [en]

    The surface chemical structure of two raw materials (agarose and dextran) and four base matrixes used in the manufacture of chromatography media were analyzed using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The results show that the small differences in molecular structure between these materials result in significant differences in the TOF-SIMS spectra and that these differences can be identified and quantified using either of two different approaches. In a novel approach, fragment ion distributions were extracted from the TOF-SIMS spectra for each material, providing an immediate and systematic overview of the spectral features. Difference fragment distributions were used to highlight spectral differences between the materials. The results of the fragment ion distribution analysis, in terms of identification and quantification of spectral variations between different materials, were found to be in agreement with the results from a principal component analysis using the same set of data. Both methods were found capable of (i) distinguishing between agarose and dextran and (ii) detecting and quantifying the degree of cross-linking present in the four base matrix materials. In addition, using a deuterated chemical cross-linker, it was possible to identify spectral features specifically connected to the cross-link molecular structure.

    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-234612 (URN)10.1021/ac035457g (DOI)15053644 (PubMedID)
    Available from: 2014-10-23 Created: 2014-10-21 Last updated: 2017-12-05Bibliographically approved
    7. Chemical characterisation of different separation media based on agarose by static time-of-flight secondary ion mass spectrometry
    Open this publication in new window or tab >>Chemical characterisation of different separation media based on agarose by static time-of-flight secondary ion mass spectrometry
    2004 (English)In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1023, no 1, p. 49-56Article in journal (Refereed) Published
    Abstract [en]

    In this paper, the novel application of time-of-flight secondary ion mass spectrometry (TOF-SIMS) for qualitative and semi-quantitative investigation of the surface chemistry of separation media based on beaded agarose is reported. Five different media were studied: DEAE Sepharose Fast Flow, Q Sepharose Fast Flow, SP Sepharose Fast Flow, Phenyl Sepharose Fast Flow at ligand densities between 7 and 33% (w/w) and the base matrix Sepharose 6 Fast Flow. The obtained TOF-SIMS spectra reveal significant chemical information regarding the ligands (DEAE, Q, SP and Phenyl) which are covalently attached to the agarose-based matrix Sepharose 6 Fast Flow. For the anion-exchange media (DEAE and Q Sepharose Fast Flow), the positive TOF-SIMS spectra yielded several strong characteristic fragment peaks from the amine ligands. Structural information was obtained, e.g. from the peak at m/z 173.20, originating from the ion structure [(C2H5)2NCH2CH2NH(C2H5)2l+, which shows that the ligand in DEAE Sepharose Fast Flow is composed of both tertiary and quaternary amines. The positive spectrum of Phenyl Sepharose Fast Flow contained major fragments both from the base matrix and the ligand. The cation-exchanger (SP Sepharose Fast Flow) gave rise to a positive spectrum resembling that of the base matrix (Sepharose 6 Fast Flow) but with a different intensity pattern of the matrix fragments. In addition, peaks with low intensity at m/z 109.94, 125.94 and 139.95 corresponding to Na2SO2+, Na2SO3+ and Na2SO3CH2+, respectively, were observed. The positive TOF-SIMS spectrum of Sepharose 6 Fast Flow contains a large number of fragments in the mass range up to m/z 200 identified as CxHyOz and CxHy structures. The results clearly show that positive TOF-SIMS spectra of different media based on Sepharose 6 Fast Flow are strongly influenced by the ligand coupled to the matrix. The negative TOF-SIMS spectra contained several ligand-specific, characteristic peaks for the cation-exchanger, having sulphonate as the ion-exchange group. Negative fragments such as S-, SO-, SO2-, SO3-, C2H3SO3-, C3H5SO3- and OC3H5SO3- were observed. Phenyl Sepharose Fast Flow, which has an uncharged group (Phenyl) coupled to the agarose matrix yielded one ligand-related peak corresponding to the C6H5O- fragment. DEAE and Q ligands could only be identified by the appearance of the fragments CN- and CNO- in the negative spectrum. However, a strong peak corresponding to the counter ion (Cl-) was observed. TOF-SIMS analysis can also be used for the investigation of residues from the coupling procedure that bonds the ligands to the matrix. One example is the observation of bromine peaks in the negative spectrum of Q Sepharose Fast Flow. Furthermore, it has also been shown that different ligand concentrations of Phenyl Sepharose Fast Flow can easily be detected by TOF-SIMS analysis. Information regarding the difference between the ligand density on the surface of the beads and in the bulk can also be obtained. However, spectra registered on the outermost surface and on the pore surface (crushed beads) of DEAE Sepharose Fast Flow clearly show that the agarose and the DEAE groups are homogeneously distributed in the beads.

    National Category
    Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-234613 (URN)10.1016/j.chroma.2003.10.008 (DOI)14760849 (PubMedID)
    Available from: 2014-10-23 Created: 2014-10-21 Last updated: 2017-12-05Bibliographically approved
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  • 32. Andersson, Mikael
    et al.
    Drevin, Ingrid
    Johansson, Bo-Lennart
    Characterization of the Chemical and Functional Stability of DEAE Sepharose Fast Flow1993In: Process Biochemistry, ISSN 1359-5113, E-ISSN 1873-3298, Vol. 28, no 4, p. 223-230Article in journal (Refereed)
    Abstract [en]

    The release of amines from the ion-exchange groups in DEAE Sepharose® Fast Flow has been studied under static and column conditions. The leakage compounds have been identified and quantified by gas chromatography—mass spectrometry. It was shown that the main leakage product under acidic (pH 1) and basic conditions (pH 14) was N,N,N′,N′-tetraethylethylenediamine. Three other amines were also identified, namely N,N,N′-triethylethylenediamine, diethylaminoethanol and diethylamine. The leakage of amines from DEAE Sepharose Fast Flow treated at pH 1 or 14 for 672 h at 40°C corresponds to a reduction of only 1% of the total ion-exchange capacity.

    The functional stability of DEAE Sepharose Fast Flow was also studied by separation of a protein mixture during repeated cleaning-in-place treatments with 0·10 m HCl or 1·0 m NaOH. The separation behaviour was unaltered after the gel had been treated for a total contact time of 672 h with 0·10 m HCl or 1·0 m NaOH.

    The clearance of ethanol from a DEAE Sepharose Fast Flow column stored in a 20% ethanol aqueous solution was also studied.

  • 33. Andersson, Mikael
    et al.
    Gustavsson, Jan
    Johansson, Bo-Lennart
    Evaluation of Several Anion-exchange Media for process Separations Using a Variety of Proteins and Aromatic Acids2001In: International Journal of Bio-Chromatography, ISSN 1068-0659, Vol. 6, p. 285-301Article in journal (Refereed)
  • 34. Andersson, Mikael
    et al.
    Knuuttila, Karl-Gustav
    The multivariate use of vibrational spectroscopy for chemical characterisation of chromatography media2002In: Vibrational Spectroscopy, ISSN 0924-2031, E-ISSN 1873-3697, Vol. 29, p. 133-138Article in journal (Refereed)
  • 35. Andersson, Mikael
    et al.
    Ramberg, Mats
    Johansson, Bo-Lennart
    The Influence of the Degree of Cross-linking, Type of Ligand and Support on the Chemical Stability of Chromatography Media Intended for protein Purification1998In: Process Biochemistry, ISSN 1359-5113, E-ISSN 1873-3298, Vol. 33, no 1, p. 47-55Article in journal (Refereed)
    Abstract [en]

    The release of organic compounds from different liquid chromatography media in static conditions has been analysed with a total organic carbon (TOC) analyser. TOC results show that chemical stability increases with the degree of cross-linking in agarose beaded chromatography media and thus extend the working pH-range of the media. Of the unsubstituted chromatography media investigated, Sepharose® 6B, Sepharose CL-6B, Sepharose 4 Fast Flow, Sepharose 6 Fast Flow and Sepharose High Performance, the latter was the most stable medium. Sepharose High Performance releases only about 0·06% of its total carbon content after 1 week in 0·01 m HCl. Agarose beads are more stable to basic conditions (pH 14) compared with acidic conditions (pH 2). From UV spectroscopic and gel filtration results it was found that all Sepharose media release low amounts of 5-(hydroxymethyl)-2-furaldehyde and agarose fragments in acidic conditions. To investigate the effect of different ligands on chemical stability Q Sepharose 6 Fast Flow, DEAE Sepharose 6 Fast Flow, SP Sepharose 6 Fast Flow, CM Sepharose 6 Fast Flow, Phenyl Sepharose 6 Fast Flow, Octyl Sepharose 4 Fast Flow media were also studied under static conditions. In basic conditions it was found that all these chromatography media release carbon compounds to a higher extent than the unsubstituted Sepharose support. In addition, Hofmann elimination of Q and DEAE groups contributes to the decrease in the carbon content of the corresponding anion exchangers. During exposure to acidic conditions (pH 2) the release of carbon compounds was lower than the release from the support to which the ligands were coupled. The exceptions are Octyl Sepharose 4 Fast Flow and SP Sepharose 6 Fast Flow. In the case of Octyl Sepharose 4 Fast Flow, the ligand did not seem to influence chemical stability, whereas the SP group increases the degradation of the Sepharose support. In the case of SP Sepharose 6 Fast Flow the stability in acidic conditions can be improved by increasing the ionic strength. Anion exchangers based on different support polymers (agarose-, polystyrene-, methacrylate- and polyvinyl-based matrixes) were studied under static conditions. Agarose-based anion exchanger was the most stable in basic conditions (pH 14). In acidic conditions (pH 2) the chemical stability was about the same for many different anion exchangers.

  • 36.
    Andersson, Simon
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Metodutveckling och analys av skumdämpare, ett additiv i vattenburna färgsystem, med vätskekromatografi och masspektrometri2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Paints mostly consist of three major components which are binder, pigment/filler andsolvent. Many other components are added in smaller amount and these are calledadditives. One of these additives is defoamers which are added to the paint todecrease foam which can cause defects in the dried paint for example as pores. Thisstudy was about investigating if the defoamers can be identified and quantified withhigh performance liquid chromatography coupled to mass spectrometry. This includessample preparation, chromatographic separation and detector settings. Calibrationcurves where constructed for paints containing different concentrations of defoamerand for a paint with 0% defoamer where different concentration of defoamer whereadded. Standard addition was done for a paint. Matrix effects were investigated bycomparing signal from defoamer in MeOH compared in paint. This study showed thatthe sample preparation of paints should involve dilution in MeOH or water followedby adding of formic acid and centrifugation and filtration to avoid problems in theinstrument. It is possible to identify if a defoamer is present in paint. Quantificationhas not been achieved, due to possible matrix effects and different response whendefoamer is added to the paint before analysis compared to when the defoamer isadded in the manufacturing process.

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    fulltext
  • 37.
    Anlind, Alice
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Biology Education Centre.
    Improvments and evaluation of data processing in LC-MS metabolomics: for application in in vitro systems pharmacology2017Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The resistance of established medicines is rapidly increasing while the rate of

    discovery of new drugs and treatments have not increases during the last decades

    (Spiro et al. 2008). Systems pharmacology can be used to find new combinations or

    concentrations of established drugs to find new treatments faster (Borisy et al. 2003).

    A recent study aimed to use high resolution Liquid chromatography–mass

    spectrometry (LC-MS) for in vitro systems pharmacology, but encountered problems

    with unwanted variability and batch effects(Herman et al. 2017). This thesis builds on

    this work by improving the pipeline and comparing alternative methods and evaluating

    used methods. The evaluation of methods indicated that the data quality was often

    not improved substantially by complex methods and pipelines. Instead simpler

    methods such as binning for feature extraction performed best. In-fact many of the

    preprocessing method commonly used proved to have negative or neglect-able effects

    on resulting data quality. Finally the recently introduced Optimal Orthonormal System

    for Discriminant Analysis (OOS-DA) for batch removal was found to be a good

    alternative to the more complex Combat method.

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  • 38.
    Aquilonius, Sten-Magnus
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Dahllöf, Tell Åke
    Droger och desperation i skilda världar: missbruk av katinon och metkatinon hotar hälsa och social utveckling.2009In: Läkartidningen, ISSN 0023-7205, E-ISSN 1652-7518, Vol. 106, no 20, p. 1358-1361Article, review/survey (Other academic)
    Abstract [sv]

    De betydande sociala och medicinska riskerna vid missbruk av katinon (tuggning av kat) och metkatinon (intravenös injektion av illegala synteser) har i stort sett inte uppmärksammats i svensk narkotikadebatt.

    Tullens beslag av kat visar hur det traditionella bruket importeras med immigration från framför allt Östafrika.

    Syntesrecept på metkatinon, som kan hämtas från Internet, ger produkter som orsakat manganförgiftning med svåra, irreversibla motoriska handikapp hos hundratals unga framför allt i Baltikum, Ryssland, Ukraina och Georgien. Denna »epidemi« fortgår.

    Kunskap om förekomst, kliniska symtom och spridningsrisker vid dessa missbruksformer är angelägen såväl ur ett nationellt som ett internationellt biståndsperspektiv.

  • 39.
    Arnell, Robert
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Surface Biotechnology.
    Fornstedt, Torgny
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Validation of the Tracer-Pulse Method for Multi-Component Liquid Chromatography. A Classical Paradox Revisited2006In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 78, no 13, p. 4615-4623Article in journal (Refereed)
    Abstract [en]

    The tracer-pulse method was extended and validated for the determination of multicomponent adsorption isotherms in liquid chromatography. Competitive adsorption isotherms can be determined for any number of solutes, up to the column resolution limit. The basic principle is to equilibrate the column with an eluent containing a mixture of the solutes and then measure the migration velocity of each of them through the column. It is easy to calculate the stationary phase concentrations from these velocities, given the eluent composition. As in frontal analysis, real competitive isotherm data are measured using this method, unlike other methods, which only produce parametric estimates. The method was used to measure the binary isotherms of beta-blockers on a Kromasil C8 column. The data were fitted to competitive bi-Langmuir adsorption isotherm functions and was found to agree well with the results of frontal analysis and the perturbation method. Computer simulations based on the isotherm parameters were performed and displayed very good agreement with the experimental chromatograms. An intriguing and seemingly paradoxical property is visualized and discussed: the fact that the injected molecules are not found in the detected peaks.

  • 40.
    Arnell, Robert
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Surface Biotechnology. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Forssén, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    Fornstedt, Torgny
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Surface Biotechnology. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Accurate and rapid estimation of adsorption isotherms in liquid chromatography using the inverse method on plateaus2005In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1099, p. 167-174Article in journal (Refereed)
  • 41.
    Arnell, Robert
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Forssén, Patrik
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing.
    Fornstedt, Torgny
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Surface Biotechnology.
    Tuneable Peak Deformations in Chiral Liquid Chromatography2007In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 79, p. 5838-5847Article in journal (Refereed)
  • 42.
    Artemenko, Konstantin A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Lind, Sara Bergström
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology.
    Elfineh, Lioudmila
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Genomics.
    Mayrhofer, Corina
    Zubarev, Roman A.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
    Pettersson, Ulf
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Genomics.
    Optimization of immunoaffinity enrichment and detection: toward a comprehensive characterization of the phosphotyrosine proteome of K562 cells by liquid chromatography-mass spectrometry2011In: The Analyst, ISSN 0003-2654, E-ISSN 1364-5528, Vol. 136, no 9, p. 1971-1978Article in journal (Refereed)
    Abstract [en]

    Phosphorylation of protein tyrosine residues regulates many cell functions and has also been proved to be involved in oncogenesis. Thus, the identification of the phosphotyrosine (pTyr) proteome of cells is a very important task. Since tyrosine phosphorylation represents only around 1% of the total human phosphoproteome, the study of pTyr proteins is rather challenging. Here we report the optimization study of the phosphotyrosine proteome using K562 cells as a model system. A substantial segment of the phosphotyrosine proteome of K562 cells was characterized by immunoaffinity enrichment with 4G10 and PYKD1 antibodies followed by LC-MS/MS analysis. 480 non-redundant pTyr peptides corresponding to 342 pTyr proteins were found. 141 pTyr peptides were not described elsewhere. The mass spectrometry approach involving high-resolving FTMS analysis of precursor ions and subsequent detection of CID fragments in a linear ion trap was considered as optimal. For detection of low abundant pTyr peptides pooling of individual immunoaffinity enrichments for one LC-MS/MS analysis was crucial. The enrichment properties of the monoclonal PYKD1 antibody were presented for the first time, also in comparison to the 4G10 antibody. PYKD1 was found to be more effective for protein enrichment (1.2 and 5% efficiency at peptide and protein level correspondingly), while 4G10 showed better results when peptide enrichment was performed (15% efficiency versus 3.6% at protein level). Substantially different subsets of the phosphoproteome were enriched by these antibodies. This finding together with previous studies demonstrates that comprehensive pTyr proteome characterization by immunoprecipitation requires multiple antibodies to be used for the affinity enrichment.

  • 43.
    Artemenko, Konstantin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Horakova, Jana
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Steinberger, Birgit
    Besenfelder, Urban
    Brem, Gottfried
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Mayrhofer, Corina
    A proteomic approach to monitor the dynamic response of the female oviductal epithelial cell surface to male gametes2015In: Journal of Proteomics, ISSN 1874-3919, E-ISSN 1876-7737, Vol. 113, p. 1-14Article in journal (Refereed)
    Abstract [en]

    UNLABELLED: Sophisticated strategies to analyze cell surface proteins are indispensable to study fundamental biological processes, such as the response of cells to environmental changes or cell-cell communication. Herein, we describe a refined mass spectrometry-based approach for the specific characterization and quantitation of cell surface proteins expressed in the female reproductive tract. The strategy is based on in situ biotinylation of rabbit oviducts, affinity enrichment of surface exposed biotin tagged proteins and dimethyl labeling of the obtained tryptic peptides followed by LC-MS/MS analysis. This approach proved to be sensitive enough to analyze small sample amounts (<1mug) and allowed further to trace the dynamic composition of the surface proteome of the oviductal epithelium in response to male gametes. The relative protein expression ratios of 175 proteins were quantified. Thirty-one of them were found to be altered over time, namely immediately, 1h and 2h after insemination compared to the time-matched control groups. Functional analysis demonstrated that structural reorganization of the oviductal epithelial cell surface was involved in the early response of the female organ to semen. In summary, this study outlines a workflow that is capable to monitor alterations in the female oviduct that are related to key reproductive processes in vivo. BIOLOGICAL SIGNIFICANCE: The proper interaction between the female reproductive tract, in particular, the oviduct and the male gametes, is fundamental to fertilization and embryonic development under physiological conditions. Thereby the oviductal epithelial cell surface proteins play an important role. Besides their direct interaction with male gametes, these molecules participate in signal transduction and, thus, are involved in the mandatory cellular response of the oviductal epithelium. In this study we present a refined LC-MS/MS based workflow that is capable to quantitatively analyze the expression of oviductal epithelial cell surface proteins in response to insemination in vivo. A special focus was on the very early interaction between the female organ and the male gametes. At first, this study clearly revealed an immediate response of the surface proteome to semen, which was modulated over time. The described methodology can be applied for studies of further distinct biological events in the oviduct and therefore contribute to a deeper insight into the formation of new life.

  • 44.
    Artemenko, Konstantin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Sui, Ping
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Watanabe, Hiroyuki
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Bergquist, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Bakalkin, Georgy
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences.
    Lateralized proteome response to the left and right side neuropathic pain in a rat modelManuscript (preprint) (Other academic)
  • 45. Ashrafian, Hutan
    et al.
    Sounderajah, Viknesh
    Glen, Robert
    Ebbels, Timothy
    Blaise, Benjamin J
    Kalra, Dipak
    Kultima, Kim
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Cancer Pharmacology and Computational Medicine. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Chemistry.
    Spjuth, Ola
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmaceutical Biosciences. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Tenori, Leonardo
    Salek, Reza M
    Kale, Namrata
    Haug, Kenneth
    Schober, Daniel
    Rocca-Serra, Philippe
    O'Donovan, Claire
    Steinbeck, Christoph
    Cano, Isaac
    de Atauri, Pedro
    Cascante, Marta
    Metabolomics: The Stethoscope for the Twenty-First Century2021In: Medical principles and practice, ISSN 1011-7571, E-ISSN 1423-0151, Vol. 30, no 4, p. 301-310Article in journal (Refereed)
    Abstract [en]

    Metabolomics encompasses the systematic identification and quantification of all metabolic products in the human body. This field could provide clinicians with novel sets of diagnostic biomarkers for disease states in addition to quantifying treatment response to medications at an individualized level. This literature review aims to highlight the technology underpinning metabolic profiling, identify potential applications of metabolomics in clinical practice, and discuss the translational challenges that the field faces. We searched PubMed, MEDLINE, and EMBASE for primary and secondary research articles regarding clinical applications of metabolomics. Metabolic profiling can be performed using mass spectrometry and nuclear magnetic resonance-based techniques using a variety of biological samples. This is carried out in vivo or in vitro following careful sample collection, preparation, and analysis. The potential clinical applications constitute disruptive innovations in their respective specialities, particularly oncology and metabolic medicine. Outstanding issues currently preventing widespread clinical use are scalability of data interpretation, standardization of sample handling practice, and e-infrastructure. Routine utilization of metabolomics at a patient and population level will constitute an integral part of future healthcare provision.

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  • 46.
    Axén, Jakob
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Malmström, David
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Axelsson, Bengt-Olof
    Petersson, Patrik
    Sjöberg, Per J. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry.
    Efforts to improve detection sensitivity for capillary electrophoresis coupled to atmospheric pressure photoionization mass spectrometry.2010In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, E-ISSN 1097-0231, Vol. 24, no 9, p. 1260-1264Article in journal (Refereed)
    Abstract [en]

    Electrospray ionization performs best with volatile buffers. However, generally the best separation performance for capillary electrophoresis (CE) is achieved with non-volatile buffers. Hyphenation of CE with mass spectrometry (MS) utilizing atmospheric pressure photoionization (APPI) enables use of a wider range of separation buffers without compromising detection sensitivity. As APPI is considered to be mass flow sensitive, the use of a larger inner diameter separation capillary (75 microm) allows larger volumes to be injected, without decreased separation performance, thus providing improved sensitivity (approx. a factor of 10), compared to the use of a 25 microm capillary. However, nebulizing gas flow and position of capillary tip in the sprayer have to be carefully optimized to prevent excessive band broadening. Further improvement in sensitivity (approx. a factor of 2) was obtained by decreasing the distance between the sprayer and ionization region, indicating that a specially designed CE/APPI-MS interface for low flow rates will be favourable.

  • 47.
    Balgoma, David
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry. INRA, UR1268 BIA Biopolymeres Interact Assemblages, F-44316 Nantes, France;INRA, Oniris, Laberca, F-44307 Nantes, France.
    Guitton, Yann
    INRA, Oniris, Laberca, F-44307 Nantes, France.
    Evans, Jason J.
    Univ Massachusetts, Dept Chem, Boston, MA 02125 USA.
    Le Bizec, Bruno
    INRA, Oniris, Laberca, F-44307 Nantes, France.
    Dervilly-Pinel, Gaud
    INRA, Oniris, Laberca, F-44307 Nantes, France.
    Meynier, Anne
    INRA, UR1268 BIA Biopolymeres Interact Assemblages, F-44316 Nantes, France.
    Modeling the fragmentation patterns of triacylglycerides in mass spectrometry allows the quantification of the regioisomers with a minimal number of standards2019In: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 1057, p. 60-69Article in journal (Refereed)
    Abstract [en]

    Mass spectrometry allows the relative quantification of the regioisomers of triacylglycerides by the calibration of their fragmentation patterns. However, due to the plethora of regioisomers of triacylglycerides, calibration with every standard is not feasible. An analytical challenge in the field is the prediction of the fragmentation patterns of triacylglycerides to quantify their regioisomers. Thus, we aimed to model these fragmentation patterns to quantify the regioisomeric composition, even for those without commercially available standards. In a first step, we modeled the fragmentation patterns of the regioisomers of triacylglycerides obtained from different published datasets. We found the same qualitative trends of fragmentation beyond differences in the type of adduct in these datasets (both [M+NH4]+ and [M+H]+), and the type of instrument (orbitrap, Q-ToF, ion-trap, single quadrupole, and triple quadrupole). However, the quantitative trends of fragmentation were adduct and instrument specific. From these observations, we modeled quantitatively the common trends of fragmentation of triacylglycerides in every dataset. In a second step, we applied this methodology on a Synapt G2S Q-ToF to quantify the regioisomers of triacylglycerides in sunflower and olive oils. The results of our quantification were in good agreement with previous published quantifications of triacylglycerides, even for regioisomers that were not present in the training dataset. The species with more than two highly unsaturated fatty acids (arachidonic, eicosapentaenoic, and docosahexaenoic acids) showed a complex behavior and lower predictability of their fragmentation patterns. However, this framework presents the capacity to model this behavior when more data are available. It would be also applicable to standardize the quantification of the regioisomers of triacylglycerides in an inter-laboratory ring study.

  • 48.
    Barclay, K.H.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry.
    A liquid chromatography-tandem mass spectrometry method for the trace analysis of diazepam and nordiazepam in environmental water samples. A comprehensive study of storage conditions and identification of an unknown compound.Manuscript (preprint) (Other academic)
  • 49.
    Barclay, Victoria K H
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Tyrefors, Niklas L
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Johansson, I Monika
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Pettersson, Curt E
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Trace analysis of fluoxetine and its metabolite norfluoxetine. Part II: Enantioselective quantification and studies of matrix effects in raw and treated wastewater by solid phase extraction and liquid chromatography-tandem mass spectrometry2012In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1227, p. 105-114Article in journal (Refereed)
    Abstract [en]

    The isotope-labeled compounds fluoxetine-d5 and norfluoxetine-d5 were used to study matrix effects caused by co-eluting compounds originating from raw and treated wastewater samples, collected in Uppsala, Sweden. The matrix effects were investigated by the determination of matrix factors (MF) and by a post-column infusion method. The matrix factors were determined to be 38–47% and 71–86% for the enantiomers of norfluoxetine-d5 and fluoxetine-d5, respectively. The influence of matrix effects when quantifying the enantiomers of the active pharmaceutical ingredient and the metabolite in wastewater samples with LC–MS/MS is discussed and methods to overcome the problem are presented. The enantiomeric concentrations of fluoxetine and its human metabolite norfluoxetine, quantified by a one-point calibration method, were 12–52 pM (3.5–16 ng L−1) in raw wastewater and 4–48 pM (1.2–15 ng L−1) in treated wastewater. Furthermore, the calculated enantiomeric fractions (EF) of the substances were found to be between 0.68 and 0.71 in both matrices. Neither the EF values for fluoxetine nor those for norfluoxetine were significantly different in the raw wastewater compared to the treated wastewater. Interestingly, the concentration of (S)-fluoxetine was found to be higher than the concentration of (R)-fluoxetine in both raw and treated wastewater. These results are different from other results presented in the literature, which shows that the relative concentrations of the enantiomers of a chiral active pharmaceutical ingredient might be significantly different in wastewater samples from different treatment systems. We report, for the first time, the concentrations of the enantiomers of norfluoxetine in wastewater samples. The concentrations of (S)-norfluoxetine were found to be higher than the concentration of (R)-norfluoxetine in the raw as well as in the treated wastewater samples.

  • 50.
    Barclay, Victoria K.H.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Medicinal Chemistry, Analytical Pharmaceutical Chemistry.
    Development of LC-MS/MS Methods for the Analysis of Chiral and Achiral Pharmaceuticals and Metabolites in Aqueous Environmental Matrices2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis describes the development of liquid chromatography tandem mass spectrometry (LC-MS/MS) methods for the trace analysis of active pharmaceutical ingredients (APIs) and their metabolites in aqueous environmental matrices. The research was focused on the development of chiral LC-MS/MS methods for the analysis of fluoxetine and metoprolol, as well as their chiral metabolites in environmental water samples. A method was also developed for the achiral compounds, diazepam and nordiazepam.

    The LC-MS/MS methods were validated by the use of the isotope-labeled compounds. As these isotope-labeled compounds were not found in the wastewater samples, the validation could be assessed at trace level concentrations in the actual matrices in which the analytes were detected.

    The analytes were extracted from the water samples using solid phase extraction methods. Different types of solid phase extraction sorbents were evaluated. Fluoxetine and norfluoxetine were extracted through the use of a mixed mode polymeric based extraction sorbent. A hydrophilic and lipophilic balanced sorbent was employed for the simultaneous extraction of metoprolol and its metabolites, the base α-hydroxymetoprolol and the acidic metabolite deaminated metoprolol. Moreover, silica based C18 extraction discs were applied for the sample preparation of diazepam and nordiazepam.

    The chromatographic separations were conducted in reversed phase LC with MS compatible mobile phases. The enantiomers of fluoxetine and norfluoxetine were simultaneously separated using the chiral stationary phase (CSP), α1-acid glycoprotein (AGP). The Chiral AGP column was also applied for the separation of the enantiomers of deaminated metoprolol. For the simultaneous separation of the metoprolol enantiomers and the four stereoisomers of α-hydroxymetoprolol, the cellobiohydrolase (CBH) protein based CSP was used. An octadecyl silica based LC column was applied for the separation of diazepam and nordiazepam.

    The analytes were detected by the use of tandem quadrupole mass spectrometry operating in selective reactive monitoring mode. High resolution MS, employing a quadrupole time-of-flight (QqTOF) mass analyzer, was utilized for the identification of an unknown compound in wastewater samples.

    The APIs and their metabolites, as well as their respective enantiomers, were quantified in raw and treated wastewater from Uppsala, Sweden along with surface water from the River Fyris in Uppsala.

    List of papers
    1. Trace analysis of fluoxetine and its metabolite norfluoxetine: Part I: Development of a chiral liquid chromatography-tandem mass spectrometry method for wastewater samples
    Open this publication in new window or tab >>Trace analysis of fluoxetine and its metabolite norfluoxetine: Part I: Development of a chiral liquid chromatography-tandem mass spectrometry method for wastewater samples
    2011 (English)In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1218, no 33, p. 5587-5596Article in journal (Refereed) Published
    Abstract [en]

    An enantioselective method for the determination of fluoxetine (a selective serotonin reuptake inhibitor) and its pharmacologically active metabolite norfluoxetine has been developed for raw and treated wastewater samples. The stable isotope-labeled fluoxetine and norfluoxetine were used in an extended way for extraction recovery calculations at trace level concentrations in wastewater. Wastewater samples were enriched by solid phase extraction (SPE) with Evolute CX-50 extraction cartridges. The obtained extraction recoveries ranged between 65 and 82% in raw and treated wastewater at a trace level concentration of 50 pM (15-16 ng L(-1)). The target compounds were identified by the use of chiral liquid chromatography tandem mass spectrometry (LC-MS/MS) in selected reaction monitoring (SRM) mode. The enantiomers were successfully resolved on a chiral alpha(1)-acid glycoprotein column (chiral AGP) with acetonitrile and 10 mM ammonium acetate buffer at pH 4.4 (3/97, v/v) as the mobile phase. The effects of pH, amount of organic modifier and buffer concentration in the mobile phase were investigated on the enantiomeric resolution (R(s)) of the target compounds. Enantiomeric R(s)-values above 2.0 (1.03 RSD%, n = 3) were achieved for the enantiomers of fluoxetine and norfluoxetine in all mobile phases investigated. The method was validated by assessing parameters such as cross-contamination and carryover during SPE and during LC analysis. Cross-talk effects were examined during the detection of the analytes in SRM mode. In addition, the isotopic purity of fluoxetine-d(5) and norfluoxetine-d(5) were assessed to exclude the possibility of self-contamination. The interassay precision of the chromatographic separation was excellent, with relative standard deviations (RSD) equal to or lower than 0.56 and 0.81% in raw and treated wastewaters, respectively. The method detection and quantification limits (respectively, MDL and MQL) were determined by the use of fluoxetine-d5 and norfluoxetine-d5. The MQL for the single enantiomers ranged from 12 to 14 pM (3.6-4.3 ng L(-1)) in raw wastewater and from 3 to 4 pM (0.9-1 ng L(-1)) in treated wastewater. The developed method has been employed for the quantification of (R)-fluoxetine, (S)-fluoxetine and the enantiomers of norfluoxetine in raw and treated wastewater samples to be presented in Part II of this study.

    Keywords
    Wastewater, Solid phase extraction, Fluoxetine, Norfluoxetine, Isotope-labeled compounds, Chiral LC-MS/MS
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-158308 (URN)10.1016/j.chroma.2011.06.024 (DOI)000294031700004 ()
    Available from: 2011-09-06 Created: 2011-09-06 Last updated: 2022-01-28Bibliographically approved
    2. Trace analysis of fluoxetine and its metabolite norfluoxetine. Part II: Enantioselective quantification and studies of matrix effects in raw and treated wastewater by solid phase extraction and liquid chromatography-tandem mass spectrometry
    Open this publication in new window or tab >>Trace analysis of fluoxetine and its metabolite norfluoxetine. Part II: Enantioselective quantification and studies of matrix effects in raw and treated wastewater by solid phase extraction and liquid chromatography-tandem mass spectrometry
    2012 (English)In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1227, p. 105-114Article in journal (Refereed) Published
    Abstract [en]

    The isotope-labeled compounds fluoxetine-d5 and norfluoxetine-d5 were used to study matrix effects caused by co-eluting compounds originating from raw and treated wastewater samples, collected in Uppsala, Sweden. The matrix effects were investigated by the determination of matrix factors (MF) and by a post-column infusion method. The matrix factors were determined to be 38–47% and 71–86% for the enantiomers of norfluoxetine-d5 and fluoxetine-d5, respectively. The influence of matrix effects when quantifying the enantiomers of the active pharmaceutical ingredient and the metabolite in wastewater samples with LC–MS/MS is discussed and methods to overcome the problem are presented. The enantiomeric concentrations of fluoxetine and its human metabolite norfluoxetine, quantified by a one-point calibration method, were 12–52 pM (3.5–16 ng L−1) in raw wastewater and 4–48 pM (1.2–15 ng L−1) in treated wastewater. Furthermore, the calculated enantiomeric fractions (EF) of the substances were found to be between 0.68 and 0.71 in both matrices. Neither the EF values for fluoxetine nor those for norfluoxetine were significantly different in the raw wastewater compared to the treated wastewater. Interestingly, the concentration of (S)-fluoxetine was found to be higher than the concentration of (R)-fluoxetine in both raw and treated wastewater. These results are different from other results presented in the literature, which shows that the relative concentrations of the enantiomers of a chiral active pharmaceutical ingredient might be significantly different in wastewater samples from different treatment systems. We report, for the first time, the concentrations of the enantiomers of norfluoxetine in wastewater samples. The concentrations of (S)-norfluoxetine were found to be higher than the concentration of (R)-norfluoxetine in the raw as well as in the treated wastewater samples.

    National Category
    Analytical Chemistry Pharmaceutical Sciences Medicinal Chemistry
    Identifiers
    urn:nbn:se:uu:diva-170511 (URN)10.1016/j.chroma.2011.12.084 (DOI)000301563700013 ()22265784 (PubMedID)
    Available from: 2012-03-12 Created: 2012-03-12 Last updated: 2018-01-12Bibliographically approved
    3. Chiral analysis of metoprolol and two of its metabolites, alpha‑hydroxymetoprolol and deaminated metoprolol, in wastewater using liquid chromatography-tandem mass spectrometry
    Open this publication in new window or tab >>Chiral analysis of metoprolol and two of its metabolites, alpha‑hydroxymetoprolol and deaminated metoprolol, in wastewater using liquid chromatography-tandem mass spectrometry
    2012 (English)In: Journal of Chromatography A, ISSN 0021-9673, E-ISSN 1873-3778, Vol. 1269, no SI, p. 208-217Article in journal (Refereed) Published
    Abstract [en]

    A LC–MS/MS method for the chiral separation of metoprolol and two of its main metabolites, α-hydroxymetoprolol (α-OH-Met) and deaminated metoprolol (COOH-Met), in environmental water samples has been developed. The target bases, metoprolol and α-OH-Met, as well as the acidic metabolite (COOH-Met) were extracted from water samples by a solid phase extraction method employing Oasis HLB cartridges. The extraction recoveries were ≥73% for all compounds in surface water. Four different types of chiral stationary phases were investigated for the separation of the eight stereoisomers of metoprolol and its metabolites, Chiralcel OD-H, Chirobiotic V, Chiral AGP and Chiral CBH. In the final method, the enantiomers of metoprolol and four stereoisomers of α-OH-Met were separated using Chiral CBH, the enantiomers of COOH-Met were separated employing Chiral AGP. The analytes were detected in SRM mode by triple quadrupole mass spectrometry. The method was applied for the chiral analysis of the analytes in treated wastewater samples from Uppsala, Sweden. The enantiomers and diastereoisomers of α-OH-Met were detected and analyzed in the samples. The concentrations of the three first eluting stereoisomers of α-OH-Met were between 54 and 61 pM. Interestingly, the last eluting stereoisomer was found to be present at a concentration of 151 pM at the same sampling occasion. This is, to the best of the authors’ knowledge, the first time the stereoisomers of α-OH-Met have been detected in wastewater samples. The enantiomers of metoprolol were determined to be 1.77 and 1.86 nM in the same matrix. The enantiomers of COOH-Met were not detected above the method detection limit (42 pM) in treated wastewater samples. The developed LC–MS/MS methods were validated in wastewater samples.

    National Category
    Pharmaceutical Sciences Analytical Chemistry
    Research subject
    Analytical Pharmaceutical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-171547 (URN)10.1016/j.chroma.2012.09.090 (DOI)000312475300016 ()
    Available from: 2012-03-21 Created: 2012-03-21 Last updated: 2018-01-12Bibliographically approved
    4. A liquid chromatography-tandem mass spectrometry method for the trace analysis of diazepam and nordiazepam in environmental water samples. A comprehensive study of storage conditions and identification of an unknown compound.
    Open this publication in new window or tab >>A liquid chromatography-tandem mass spectrometry method for the trace analysis of diazepam and nordiazepam in environmental water samples. A comprehensive study of storage conditions and identification of an unknown compound.
    (English)Manuscript (preprint) (Other academic)
    National Category
    Pharmaceutical Sciences Analytical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-171548 (URN)
    Available from: 2012-03-21 Created: 2012-03-21 Last updated: 2018-01-12
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