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Determination of hydroxyalkyl derivatives of cobalamin (vitamin B12) using reversed phase high performance liquid chromatography with electrospray tandem mass spectrometry and ultraviolet diode array detection
Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
Stockholm University, Faculty of Science, Department of Environmental Chemistry.
Stockholm University, Faculty of Science, Department of Environmental Chemistry.
2001 (English)In: Rapid Communications in Mass Spectrometry, ISSN 0951-4198, Vol. 15, no 24, 2438-45 p.Article in journal (Refereed) Published
Abstract [en]

Electrospray ionization tandem mass spectrometry (ESI-MS/MS) and ultraviolet diode array detection (UV-DAD), coupled on-line to reversed phase high performance liquid chromatography (HPLC), was used for the characterization of hydroxyalkyl derivatives of cob(I)alamin. The reduced form of vitamin B12, cob(I)alamin, denoted a supernucleophile due to its high nucleophilic strength, has shown promise as an analytical tool in studies of electrophilically reactive compounds in vitro and in vivo. A method for analysis of DNA-phosphate adducts was developed earlier utilizing the supernucleophilicity of cob(I)alamin to transfer alkyl groups from the phosphotriester configuration in DNA, with the formation of a Co-substituted alkyl-cobalamin (alkyl-Cbl) complex. For the purpose of identification and quantification of alkyl-Cbls at high sensitivity, an MS/MS method has been developed with application to a number of 2-hydroxyalkyl-cobalamins (OHalkyl-Cbls). The precursor oxiranes were reacted with cob(I)alamin, followed by clean-up and mass spectrometric analysis of the resulting OHalkyl-Cbls. It was found that ionization was highly dependent on solvent composition. By using acetonitrile/water/trifluoroacetic acid (TFA) (eluent I), the base peak was the doubly protonated molecule [M + 2H](2+), whereas acetonitrile/water/1-methylpiperidine (eluent II) yielded the singly protonated molecule [M + H](+) as the base peak. Excellent separation was obtained with eluent II, with good separation between stereoisomers, thus enabling the characterization of these by means of UV spectra. Limits of quantitation for 2-hydroxypropyl-cobalamin (OHPr-Cbl) were 0.2 and 2 pg/microL (or 0.1 and 1 fmol/microL) using selected ion recording (SIR) with eluent I and II, respectively. The obtained detection level should be sufficient for analysis of alkyl-Cbls from a wide range of toxicological applications.

Place, publisher, year, edition, pages
2001. Vol. 15, no 24, 2438-45 p.
Identifiers
URN: urn:nbn:se:su:diva-29178DOI: 10.1002/rcm.527PubMedID: 11746915OAI: oai:DiVA.org:su-29178DiVA: diva2:229430
Available from: 2009-08-12 Created: 2009-08-12 Last updated: 2009-08-13Bibliographically approved
In thesis
1. Development of Methods for the Analysis of Polar Compounds in Environmental Matrices using LC/UV and LC/MS
Open this publication in new window or tab >>Development of Methods for the Analysis of Polar Compounds in Environmental Matrices using LC/UV and LC/MS
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In recent years, the awareness of environmentally hazardous compounds with polar and ionizable properties has intensified. Pharmaceuticals, the pesticide tebuconazole as well as the artificial sweetener sucralose are examples of such new, emerging, contaminants. The toxicological and ecotoxicological effects of these contaminants require investigation. This has led to an increasing need for analytical methods capable of measuring polar compounds in environmental matrices.

 This thesis describes the use of liquid chromatography (LC) hyphenated with ultraviolet (UV) or mass spectrometric (MS) detection for four environmental applications. Paper I describes a method for the detection and qualitative analysis of hydroxyalkyl cobalamins using LC/MS. The method was part of a project for the determination of carcinogenic compounds bound as adducts to the DNA molecule. In paper II, a LC/UV method for the analysis of the pesticide tebuconazole was developed. The method was used to evaluate a novel ecotoxicological test system. Paper III describes an LC/MS method for the determination of the artificial sweetener sucralose in sewage and recipient water. The sucralose molecule and its fragments were found difficult to detect, and a method was developed as an alternative to multiple reaction monitoring (MRM). Both quadrupoles scanned the same ion, a novel technique hypothesized to reduce matrix effects compared to selected ion recording (SIR). Paper IV describes a method for the extraction and analysis of pharmaceuticals in sediment. The study emphasizes the evaluation of suitable solvents for the extraction of basic, neutral and acidic pharmaceuticals. It was concluded that an extraction solvent containing acetone : McIlvaine buffer (pH 4) was appropriate. Electrospray LC/MS in the MRM mode was used. Additional qualitative identification of non target pharmaceuticals was performed by accurate mass measurements utilizing a quadrupole time-of-flight (Q/TOF) instrument.

Place, publisher, year, edition, pages
Stockholm: Department of Applied Environmental Science (ITM), Stockholm University, 2009. 31 p.
National Category
Natural Sciences
Research subject
Applied Environmental Science
Identifiers
urn:nbn:se:su:diva-29108 (URN)978-91-7155-910-4 (ISBN)
Public defence
2009-09-11, De Geersalen, Geovetenskapens hus, Svante Arrhenius väg 8 A, Stockholm, 10:00 (Swedish)
Opponent
Supervisors
Note
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted.Available from: 2009-08-21 Created: 2009-08-11 Last updated: 2009-08-13Bibliographically approved

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