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On-line electrochemically controlled solid-phase extraction interfaced to electrospray and inductively coupled plasma mass spectrometry
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Chemistry, Department of Chemistry, Analytical Chemistry.
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2005 In: The Analyst, ISSN 0003-2654, Vol. 130, no 10, 1358-1368 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2005. Vol. 130, no 10, 1358-1368 p.
Identifiers
URN: urn:nbn:se:uu:diva-96097OAI: oai:DiVA.org:uu-96097DiVA: diva2:170560
Available from: 2007-09-04 Created: 2007-09-04Bibliographically approved
In thesis
1. Inductively Coupled Plasma Spectrometry for Speciation Analysis: Development and Applications
Open this publication in new window or tab >>Inductively Coupled Plasma Spectrometry for Speciation Analysis: Development and Applications
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In analytical chemistry the main goal is normally to determine the identity and/or concentration of one or more species in a sample. The samples analyzed are often natural samples, containing numerous different species in a complex matrix and the choice of technique for multi-elemental detection is in general inductively coupled plasma spectrometry. The chemical forms of an element can affect many of its characteristics e.g. toxicity, which makes speciation analysis important. Therefore, determination of the identity and quantity of an element is still important, but for many applications measurements of total element concentration provides insufficient information. To be able to perform speciation analysis, separation, identification and/or characterization of the various forms of elements in the sample has to be accomplished. Speciation analysis has been employed in a wide range of disciplines, including for example environmental science, biology and clinical chemistry.

This thesis describes work to improve and understand the elemental speciation analysis with liquid chromatography coupled to plasma spectrometry and also highlights the importance and potential of the synergy between atomic spectrometry and molecular mass spectrometry. The combination of the matrix tolerant, robust and very sensitive plasma spectrometry used together with molecular mass spectrometry, which provides structural information and the possibility to identify unknown species, is demonstrated to be a very powerful tool for speciation analysis. In this thesis methods are developed for on-line sample clean-up and pre-concentration coupled to liquid chromatography and plasma spectrometry, which makes handling of small sample volumes easier and also decreases the risk of contamination. The problems associated with organic modifiers in plasma spectrometry are also addressed. Applications of speciation analysis are exemplified by analysis of aluminium-chelated siderophores in field-soil solutions and organic phosphorous species in aquatic sediments. The possibility to analyze un-dissolved samples as slurries with minimal sample preparation is also discussed.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 56 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 327
Keyword
Analytical chemistry, Speciation analysis, Atomic emission spectrometry (AES), Mass spectrometry (MS), Inductively coupled plasma (ICP), Liquid Chromatography (LC), on-line sample pre-treatment, Organic phosphour, Siderophores, Slurry nebulization, matrix effects, Analytisk kemi
Identifiers
urn:nbn:se:uu:diva-8169 (URN)978-91-554-6945-0 (ISBN)
Public defence
2007-09-25, B41, BMC, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2007-09-04 Created: 2007-09-04 Last updated: 2011-05-10Bibliographically approved
2. On-line Electrochemistry Electrospray Ionisation Mass Spectrometry: Method Development and Applications
Open this publication in new window or tab >>On-line Electrochemistry Electrospray Ionisation Mass Spectrometry: Method Development and Applications
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis deals with studies of on-line electrochemistry electrospray ionisation mass spectrometry (EC/ESI-MS). It is shown that the use of EC/ESI-MS demands optimal coupling characteristics.

Pre-concentration and desalting, due to matrix exchange, were demonstrated for the model substance 1-hexanethiol in an EC/ESI-MS setup. The setup was also used for investigations of the oxidation states of the manganese complex [Mn2(bpmp)(µ-OAc)2][ClO4], where bpmp is a 2,6-bis[[N,N-di(2-pyridylmethyl)amino]methyl]-4-methylphenol compound. The manganese complex, which is relevant to artificial photosynthesis, was found to be a good model compound for the EC/ESI-MS studies, thanks to its many oxidation states. For the first time, the presence of the Mn(III,IV) state of the manganese complex was demonstrated in the studies.

During the experimental work, the importance of the electrode positioning within the electrochemical cell was investigated. Different EC cell configurations were studied using the manganese complex as a model substance. It was clearly shown that the EC cell design influences the distribution between the peaks in the mass spectra - not only for manganese complexes and Olsalazine but also for 4-chloroaniline.

A previously unknown comproportionation reaction was found for 4-chloroaniline involving the oxidised dimer, 4-[(4-chlorophenyl)imino]-2,5-cyclohexadien-1-imine. This reaction explained the unexpected presence of the signal due to the reduced dimer, 4-amino-4'-chlorodiphenylamine, in the mass spectra.

Furthermore, it was shown that EC/ESI-MS was successful in conjunction with miniaturised gold wire electrodes in a PDMS chip within which dopamine was oxidised with a conversion efficiency of 30%. The oxidation products of dopamine were detected after 0.6-1.2 seconds for 1.0 and 0.5 µl/min, respectively. The combination of electrochemically controlled solid-phase extraction (EC-SPE) with ESI-MS was found to be less straightforward than detecting anions pre-concentrated on a polypyrrole coated electrode with EC-SPE/ICP-MS.

The on-line combination of liquid chromatography with EC/ESI-MS/MS for studying antioxidants in yellow onion extracts was shown to be fast and a relatively easy complement to classical antioxidant activity determinations.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 78 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 622
National Category
Chemical Sciences
Research subject
Analytical Chemistry
Identifiers
urn:nbn:se:uu:diva-99329 (URN)978-91-554-7459-1 (ISBN)
Public defence
2009-04-24, BMC, B42, Husargatan 3, Uppsala, 10:15 (English)
Opponent
Supervisors
Available from: 2009-04-02 Created: 2009-03-12 Last updated: 2009-04-06Bibliographically approved

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