uu.seUppsala University Publications
Change search
Link to record
Permanent link

Direct link
BETA
Sjöberg, Per J. R.
Alternative names
Publications (10 of 75) Show all publications
Hawkes, J. A., Sjöberg, P. J. R., Bergquist, J. & Tranvik, L. (2019). Complexity of dissolved organic matter in the molecular size dimension: insights from coupled size exclusion chromatography electrospray ionisation mass spectrometry. Faraday discussions (Online)
Open this publication in new window or tab >>Complexity of dissolved organic matter in the molecular size dimension: insights from coupled size exclusion chromatography electrospray ionisation mass spectrometry
2019 (English)In: Faraday discussions (Online), ISSN 1359-6640, E-ISSN 1364-5498Article in journal (Refereed) Epub ahead of print
Abstract [en]

This paper investigates the relationship between apparent size distribution and molecular complexity of dissolved organic matter from the natural environment. We used a high pressure size exclusion chromatography (HPSEC) method coupled to UV-Vis diode array detection (UV-DAD) and electrospray ionisation mass spectrometry (ESI-MS) in order to compare the apparent size of natural organic matter, determined by HPSEC-UV and the molecular mass determined online by ESI-MS. We found that there was a clear discrepancy between the two methods, and found evidence for an important pool of organic matter that has a strong UV absorbance and no ESI-MS signal. Contrary to some previous research, we found no evidence that apparently high molecular weight organic matter is constituted by aggregates of low molecular weight (<1000 Da) material. Furthermore, our results suggest that the majority of apparent size variability within the ESI ionisable pool of organic matter is due to secondary interaction and exclusion effects on the HPSEC column, and not true differences in hydrodynamic size or intermolecular aggregation.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-384038 (URN)10.1039/c8fd00222c (DOI)
Available from: 2019-06-04 Created: 2019-06-04 Last updated: 2019-06-10Bibliographically approved
Hawkes, J. A., Patriarca, C., Sjöberg, P. J. R., Tranvik, L. & Bergquist, J. (2018). Extreme isomeric complexity of dissolved organic matter found across aquatic environments. Limnology and Oceanography Letters, 3(2), 21-30
Open this publication in new window or tab >>Extreme isomeric complexity of dissolved organic matter found across aquatic environments
Show others...
2018 (English)In: Limnology and Oceanography Letters, E-ISSN 2378-2242, Vol. 3, no 2, p. 21-30Article in journal (Refereed) Published
Abstract [en]

The natural aquatic environment contains an enormous pool of dissolved reduced carbon, present as ultra‐complex mixtures that are constituted by an unknown number of compounds at vanishingly small concentrations. We attempted to separate individual structural isomers from several samples using online reversed‐phase chromatography with selected ion monitoring/tandem mass spectrometry, but found that isomeric complexity still presented a boundary to investigation even after chromatographic simplification of the samples. However, it was possible to determine that the structural complexity differed among samples. Our results also suggest that extreme structural complexity was a ubiquitous feature of dissolved organic matter (DOM) in all aquatic systems, meaning that this diversity may play similar roles for recalcitrance and degradation of DOM in all tested environments.

National Category
Chemical Sciences Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-369282 (URN)10.1002/lol2.10064 (DOI)000456695800001 ()
Funder
Knut and Alice Wallenberg FoundationSwedish Energy Agency
Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2019-02-12Bibliographically approved
Patriarca, C., Bergquist, J., Sjöberg, P. J., Tranvik, L. & Hawkes, J. A. (2018). Online HPLC-ESI-HRMS Method for the Analysis and Comparison of Different Dissolved Organic Matter Samples. Environmental Science and Technology, 52(4), 2091-2099
Open this publication in new window or tab >>Online HPLC-ESI-HRMS Method for the Analysis and Comparison of Different Dissolved Organic Matter Samples
Show others...
2018 (English)In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 52, no 4, p. 2091-2099Article in journal (Refereed) Published
Abstract [en]

Natural dissolved organic matter (DOM) is an ultracomplex mixture that is essential to global carbon cycling but is poorly understood because of its complexity. The most powerful tool for the DOM characterization is high-resolution mass spectrometry (HRMS) generally combined to direct infusion (DI) as sample introduction. Liquid chromatography (LC) represents a compelling alternative to DI; however, state-of-the-art techniques involve only offline LC-HRMS approaches, which have important logistical drawbacks that make DOM analysis more challenging. This study introduces a new method based on online coupling of liquid chromatography to high resolution mass spectrometry, able to overcome the disadvantages of usual approaches. It is characterized by high reproducibility (% Bray–Curtis dissimilarity among replicates ≈ 2.5%), and it reduces transient complexity and contaminant interferences, thus increasing the signal-to-noise ratio (S/N), leading to the identification of an overall larger number of formulas in the mixture. Moreover, the application of an in silico fractionation prior to the statistical analysis allows an easy, flexible, fast, and detailed comparison of DOM samples from a variety of sources with a single chromatographic run.

National Category
Analytical Chemistry
Research subject
Chemistry with specialization in Analytical Chemistry
Identifiers
urn:nbn:se:uu:diva-341015 (URN)10.1021/acs.est.7b04508 (DOI)000426143300045 ()
Funder
Knut and Alice Wallenberg Foundation, 2013.0091Swedish Research Council, SRC 2015-4870Swedish Research Council, SRC 2014-04264
Available from: 2018-02-06 Created: 2018-02-06 Last updated: 2018-12-12Bibliographically approved
Recknagel, C., Thelin, P., Abraham, M., Schulz-Bull, D. & Sjöberg, P. J. R. (2018). Using standard additions to improve extraction and quantification of inositol hexakisphosphate in sediment samples by ion chromatography electrospray ionization mass spectrometry. Talanta: The International Journal of Pure and Applied Analytical Chemistry, 188, 192-198
Open this publication in new window or tab >>Using standard additions to improve extraction and quantification of inositol hexakisphosphate in sediment samples by ion chromatography electrospray ionization mass spectrometry
Show others...
2018 (English)In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 188, p. 192-198Article in journal (Refereed) Published
Abstract [en]

Several key aspects for the analysis of inositol hexakisphosphate (InsP(6)) have been investigated in order to establish a suitable method for the study of sediment samples from different aquatic systems. Apparent matrix effects for the ion chromatography electrospray ionization tandem mass spectrometric detection (IC-ESI-MS/MS) method were accounted for with a standard addition approach, which also compensated for variation in extraction efficiency. Several parameters of the extraction method were optimized to improve the extraction efficiency for different sediment types. We observed an improvement in the extraction efficiency between 18% and 720%. Finally, the method was used to gain first insights into the relevance of InsP(6) in two aquatic systems located at the German Baltic coastal area. InsP(6) was detected in several sediment samples with concentrations between 2.3 and 15.2 mu g InsP(6)-P/g dry weight (DW).

Keywords
Inositol phosphates, IC-ESI-MS, Standard addition, Sediment
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:uu:diva-362627 (URN)10.1016/j.talanta.2018.05.072 (DOI)000440958700024 ()30029363 (PubMedID)
Funder
EU, Horizon 2020
Available from: 2018-10-10 Created: 2018-10-10 Last updated: 2018-10-10Bibliographically approved
Bunrit, A., Sawadjoon, S., Tsupova, S., Sjöberg, P. J. R. & Samec, J. S. M. (2016). A General Route to beta-Substituted Pyrroles by Transition-Metal Catalysis. Journal of Organic Chemistry, 81(4), 1450-1460
Open this publication in new window or tab >>A General Route to beta-Substituted Pyrroles by Transition-Metal Catalysis
Show others...
2016 (English)In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 81, no 4, p. 1450-1460Article in journal (Refereed) Published
Abstract [en]

An atom-efficient route to pyrroles substituted in the beta-position has been achieved in four high yielding steps by a combination of Pd, Ru, and Fe catalysis with only water and ethene as side-products. The reaction is general and gives pyrroles substituted in the beta-position with linear and branched alkyl, benzyl, or aryl groups in overall good yields. The synthetic route includes a Pd-catalyzed monoallylation step of amines with substituted allylic alcohols that proceeds to yield the monoallylated products in moderate to excellent yields. In a second step, unsymmetrical diallylated aromatic amines are generated from the reaction of a second allylic alcohol with high selectivity in moderate to good yields by control of the reaction temperature. Ru-catalyzed ring-closing metathesis performed on the diallylated aromatic amines yields the pyrrolines substituted in the beta-position in excellent yields. By addition of ferric chloride to the reaction mixture, a selective aromatization to yield the corresponding pyrroles substituted in the beta-position was achieved. A reaction mechanism involving a palladium hydride, generated from insertion of palladium to O-H of an allyl alcohol, that is responsible for the C-O bond cleavage to generate the pi-allyl intermediate is proposed.

National Category
Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-282318 (URN)10.1021/acs.joc.5b02581 (DOI)000370768000013 ()26789020 (PubMedID)
Funder
Swedish Research Council FormasStiftelsen Olle Engkvist Byggmästare
Available from: 2016-04-05 Created: 2016-04-05 Last updated: 2017-11-30Bibliographically approved
Fridén, M. E., Jumaah, F., Gustavsson, C., Enmark, M., Fornstedt, T., Turner, C., . . . Samuelsson, J. (2016). Evaluation and Analysis of Environmentally Sustainable Methodologies for Extraction of Betulin from Birch Bark with Focus on Industrial Feasibility. Green Chemistry, 18(2), 516-523
Open this publication in new window or tab >>Evaluation and Analysis of Environmentally Sustainable Methodologies for Extraction of Betulin from Birch Bark with Focus on Industrial Feasibility
Show others...
2016 (English)In: Green Chemistry, ISSN 1463-9262, E-ISSN 1463-9270, Vol. 18, no 2, p. 516-523Article in journal (Refereed) Published
Abstract [en]

Betulin from birch bark was extracted using two principally different extraction methodologies - classical Reflux Boiling (RB) and Pressurized Liquid Extraction (PLE). The extraction methods were analyzed based on both recovery and purity as well as for RB industrial feasibility. The purity and recovery for the different extraction methods were analyzed using High Performance Liquid Chromatography (HPLC) coupled with three different detection principles: Diode Array Detection (DAD), Mass Spectrometry (MS) and Charged Aerosol Detection (CAD). The chromatographic purity was determined by all detections whereas the DAD was used also for complementary gravimetric calculations of the purity of the extracts. The MS detection (in MS and MS/MS modes) was mainly used to characterize the impurities. Two steps to increase the purity of RB extracts were evaluated - pre-boiling the bark in water and precipitation by adding water to the extract. Finally, the methods were compared in terms of amounts of betulin produced and solvent consumed. The RB method including a precipitation step produced the highest purity of betulin. However, results indicate that PLE using three cycles with the precipitation step gives similar purities as for RB. The PLE method produced up to 1.6 times higher amount of extract compared to the RB method. However, the solvent consumption (liter solvent per gram product) for PLE was around 4.5 times higher as compared to the classical RB. PLE performed with only one extraction cycle gave results more similar to RB with 1.2 times higher yield and 1.4 times higher solvent consumption. The RB process was investigated on an industrial scale using a model approach and several important key-factors could be identified. The most energy demanding step was the recycling of extraction solvent which motivates that solvent consumption should be kept low and calculations show a great putative energy reduction by decreasing the ethanol concentration used in the RB process to lower than 90%.

Keywords
betulin; energy calculations; extraction; mass spectrometry; pressurized liquid extraction; purification; reflux boiling; supercritical fluid extraction
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:uu:diva-249296 (URN)10.1039/c5gc00519a (DOI)000369534500024 ()
Funder
Swedish Research Council Formas, 229-2009-1527
Available from: 2015-04-13 Created: 2015-04-13 Last updated: 2017-12-04Bibliographically approved
Bunrit, A., Dahlstrand, C., Olsson, S. K., Srifa, P., Huang, G., Orthaber, A., . . . Samec, J. S. M. (2015). Bronsted Acid-Catalyzed Intramolecular Nucleophilic Substitution of the Hydroxyl Group in Stereogenic Alcohols with Chirality Transfer. Journal of the American Chemical Society, 137(14), 4646-4649
Open this publication in new window or tab >>Bronsted Acid-Catalyzed Intramolecular Nucleophilic Substitution of the Hydroxyl Group in Stereogenic Alcohols with Chirality Transfer
Show others...
2015 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 137, no 14, p. 4646-4649Article in journal (Refereed) Published
Abstract [en]

The hydroxyl group of enantioenriched benzyl, propargyl, allyl, and alkyl alcohols has been intramolecularly displaced by uncharged O-, N-, and S-centered nucleophiles to yield enantioenriched tetrahydrofuran, pyrrolidine, and tetrahydrothiophene derivatives with phosphinic acid catalysis. The five-membered heterocyclic products are generated in good to excellent yields, with high degree of chirality transfer, and water as the only side-product. Racemization experiments show that phosphinic acid does not promote S(N)1 reactivity. Density functional theory calculations corroborate a reaction pathway where the phosphinic acid operates as a bifunctional catalyst in the intramolecular substitution reaction. In this mechanism, the acidic proton of the phosphinic acid protonates the hydroxyl group, enhancing the leaving group ability. Simultaneously, the oxo group of phosphinic acid operates as a base abstracting the nucleophilic proton and thus enhancing the nucleophilicity. This reaction will open up new atom efficient techniques that enable alcohols to be used as nucleofuges in substitution reactions in the future.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-253254 (URN)10.1021/jacs.5b02013 (DOI)000353177100014 ()25803790 (PubMedID)
Available from: 2015-06-12 Created: 2015-05-25 Last updated: 2017-12-04Bibliographically approved
Paraskova, J. V., Jorgensen, C., Reitzel, K., Pettersson, J., Rydin, E. & Sjöberg, P. J. R. (2015). Speciation of Inositol Phosphates in Lake Sediments by Ion-Exchange Chromatography Coupled with Mass Spectrometry, Inductively Coupled Plasma Atomic Emission Spectroscopy, and P-31 NMR Spectroscopy. Analytical Chemistry, 87(5), 2672-2677
Open this publication in new window or tab >>Speciation of Inositol Phosphates in Lake Sediments by Ion-Exchange Chromatography Coupled with Mass Spectrometry, Inductively Coupled Plasma Atomic Emission Spectroscopy, and P-31 NMR Spectroscopy
Show others...
2015 (English)In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 87, no 5, p. 2672-2677Article in journal (Refereed) Published
Abstract [en]

A method for the detection and speciation of inositol phosphates (InsP(n)) in sediment samples was tested, utilizing oxalateoxalic acid extraction followed by determination by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLCMS/MS) using electrospray ionization (ESI) in negative mode. The chromatographic separation was carried out using water and ammonium bicarbonate as mobile phase in gradient mode. Data acquisition under MS/MS was attained by multiple reaction monitoring. The technique provided a sensitive and selective detection of InsP(n) in sediment samples. Several forms of InsPn in the oxalateoxalic acid extracted sediment were identified. InsP(6) was the dominating form constituting 0.250 mg P/g DW (dry weight); InsP(5) and InsP(4) constituted 0.045 and 0.014 mg P/g DW, respectively. The detection limit of the LCESI-MS/MS method was 0.03 mu M InsPn, which is superior to the currently used method for the identification of InsPn, P-31 nuclear magnetic resonance spectroscopy (P-31 NMR). Additionally sample handling time was significantly reduced.

National Category
Analytical Chemistry
Identifiers
urn:nbn:se:uu:diva-251433 (URN)10.1021/ac5033484 (DOI)000350611700025 ()25649303 (PubMedID)
Available from: 2015-04-23 Created: 2015-04-17 Last updated: 2017-12-04Bibliographically approved
Sawadjoon, S., Orthaber, A., Sjöberg, P. J. R., Eriksson, L. & Samec, J. S. M. (2014). Equilibrium Study of Pd(dba)2 and P(OPh)3 in the Pd-Catalyzed Allylation of Aniline by Allyl Alcohol. Organometallics, 33(1), 249-253
Open this publication in new window or tab >>Equilibrium Study of Pd(dba)2 and P(OPh)3 in the Pd-Catalyzed Allylation of Aniline by Allyl Alcohol
Show others...
2014 (English)In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 33, no 1, p. 249-253Article in journal (Refereed) Published
Abstract [en]

Reaction of Pd(dba)2 and P(OPh)3 shows a unique equilibrium where the Pd[P(OPh)3]3 complex is favored over both Pd(dba)[P(OPh)3]2 and Pd[P(OPh)3]4 complexes at room temperature. At a lower temperature, Pd[P(OPh)3]4 becomes the most abundant complex in solution. X-ray studies of Pd[P(OPh)3]3 and Pd(dba)[P(OPh)3]2 complexes show that both complexes have a trigonal geometry with a Pd–P distance of 2.25 Å due to the π-acidity of the phosphite ligand. In solution, pure Pd(dba)[P(OPh)3]2 complex equilibrates to the favored Pd[P(OPh)3]3 complex, which is the most stable complex of those studied, and also forms the most active catalytic species. This catalyst precursor dissociates one ligand to give the reactive Pd[P(OPh)3]2, which performs an oxidative addition of nonmanipulated allyl alcohol to generate the π-allyl-Pd[P(OPh)3]2 intermediate according to ESI-MS studies.

National Category
Natural Sciences
Identifiers
urn:nbn:se:uu:diva-218947 (URN)10.1021/om4009873 (DOI)000329879900029 ()
Available from: 2014-02-27 Created: 2014-02-20 Last updated: 2017-12-05Bibliographically approved
Sawadjoon, S., Sjöberg, P. J., Orthaber, A., Matsson, O. & Samec, J. S. (2014). Mechanistic Insights into the Pd-Catalyzed Direct Amination of Allyl Alcohols: Evidence for an Outer-sphere Mechanism Involving a Palladium Hydride Intermediate. Chemistry - A European Journal, 20(6), 1520-1524
Open this publication in new window or tab >>Mechanistic Insights into the Pd-Catalyzed Direct Amination of Allyl Alcohols: Evidence for an Outer-sphere Mechanism Involving a Palladium Hydride Intermediate
Show others...
2014 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 6, p. 1520-1524Article in journal (Refereed) Published
Abstract [en]

The mechanism of direct amination of allyl alcohol by a palladium triphenylphosphite complex has been explored. Labelling studies show that the reaction proceeds through a π-allylpalladium intermediate. A second-order dependence of reaction rate on allyl alcohol concentration was observed. Kinetic isotope effect studies and ESI-MS studies are in agreement with a reaction proceeding through a palladium hydride intermediate in which both O-H bond and C-O bond cleavages are involved in rate-determining steps. A stereochemical study supports an outer-sphere nucleophilic attack of the π-allylpalladium intermediate giving complete chiral transfer from starting material to product.

National Category
Analytical Chemistry Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-215613 (URN)10.1002/chem.201303431 (DOI)000337300000008 ()24403056 (PubMedID)
Available from: 2014-01-15 Created: 2014-01-15 Last updated: 2017-12-06Bibliographically approved
Organisations

Search in DiVA

Show all publications