Authors: Lekha Sleno Michael J Chalmers Dietrich A Volmer
Publish Date: 2003/11/22
Volume: 378, Issue: 4, Pages: 977-986
Abstract
The spirolides are a family of marine biotoxins derived from the dinoflagellate Alexandrium ostenfeldii recently isolated from contaminated shellfish and characterized A crude phytoplankton extract has been extensively studied for mass spectrometric determination and characterization of several known spirolides and previously unreported compounds The complex sample was initially analyzed by fullscan mass spectrometry in an iontrap instrument enabling identification of several components Subsequent analysis by selectedion monitoring in a triplequadrupole instrument resulted in the confirmation of the identities of the compounds detected in the ion trap Purification of the crude extract was performed using an automated massbased fractionation system yielding several fractions with different relative contributions of the spirolide components Collisioninduced dissociation CID in the triplequadrupole instrument produced significant fragment ions for all identified species Selective enrichment of some minor compounds in certain fractions enabled excellent CID spectra to be generated this had previously been impossible because of interferences from the major toxins present Fouriertransform ion cyclotron resonance FTICR mass spectrometry was then performed for accurate determination of the masses of MH+ ions of all the species present in the sample Additionally infrared multiphoton dissociation in the FTICR instrument generated elemental formulae for product ions including those formed in the previous collisional activation experiments Collection of these results and the fragmentation scheme proposed for the main component of the extract 13desmethyl spirolide C from part I of this study enabled elucidation of the structures of some uncharacterized spirolides and some biogenetically related compounds present at previously unreported massesThe authors wish to thank Dr Anthony Windust NRC/IMB Halifax NS Canada for the culture of the phytoplankton and help with the partial purification of the extract and Dr Kevin Bateman Carmai Seto and Tammy LeRiche at the Merck Frosst Centre for Therapeutic Research Kirkland QC Canada for invaluable help in the masstriggered fractionation experiments LS would also like to acknowledge financial assistance from le Fonds Quebecois de la recherche sur la nature et les technologies FCAR the National Research Council’s Graduate Student Scholarship Supplement Program GSSSP and Dr Alan Cembella at the National Research Council’s Institute for Marine Biosciences This work was supported in part by the NSF National HighField FTICR MS Facility CHE9909502
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