Sokoine University of Agriculture

Thiol Derivatization for LC-MS Identification of Microcystins in Complex Matrices

Show simple item record Miles, C. O. Sandvik, M. Nonga, H. E. Rundberget, T. Wilkins, A. L. Rise, F. Ballot, A. 2018-07-13T05:36:36Z 2018-07-13T05:36:36Z 2012-07-18
dc.description Environmental science and technology, 2012; 46:8937-8944 en_US
dc.description.abstract Microcystins are a group of cyclic heptapeptides originating from cyanobacteria. Cyanobacteria also produce a range of peptides and other compounds that can result in complex chromatograms when samples are analyzed by LC-MS. Derivatization with appropriate thiols (e.g., mercaptoethanol) of the olefin in the α,β-unsaturated amide present in most microcystins was shown to simplify analysis of LC-MS chromatograms of sample extracts, making it much easier to identify peaks corresponding to candidate microcystins. Furthermore, interpretation of MS2 spectra was facilitated by addition of the mass associated with the thiol to the α,β-unsaturated amide of microcystins. Cyanotoxins containing Mdha or Dha reacted readily with thiols, whereas Mser, Ser, Mdhb, and thiol-derivatives of Mdha or Dha did not react under the conditions used. This approach therefore provides a convenient LC-MS method to obtain evidence for the presence of Mdha or Dha and can likely be used to differentiate between the isobaric amino acids Mdha and Dhb in candidate cyanotoxin peaks. When O-(2-mercaptoethyl)-O′-methyl-hexa(ethylene glycol) (MEMHEG) (Mwt. 356) was used as the thiol, the resulting derivatives eluted in an LC-MS mass window that was largely free of interferences. This approach simplifies detection of candidate microcystin analogues even in the presence of complex mixtures of coeluting components. The method was used for qualitative analysis of a Microcystis aeruginosa culture from Lake Naivasha, Kenya, and the results were verified using precursor-ion scanning and high-resolution mass spectrometry. en_US
dc.description.sponsorship SIDA SAREC: VICRES Endocrine disruptors project en_US
dc.language.iso en en_US
dc.publisher ACS Publications en_US
dc.subject Thiol Derivatization en_US
dc.subject Microcystins en_US
dc.subject Cyanobacteria en_US
dc.title Thiol Derivatization for LC-MS Identification of Microcystins in Complex Matrices en_US
dc.type Article en_US
dc.url en_US

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