DIRECT IDENTIFICATION OF YESSOTOXIN IN SHELLFISH BY LIQUID-CHROMATOGRAPHY COUPLED WITH MASS-SPECTROMETRY AND TANDEM MASS-SPECTROMETRY

A new method for the direct identification of yessotoxin (YTX), a poly ether compound belonging to the diarrhoeic shellfish poisoning (DSP) t oxins, using liquid chromatography coupled with mass spectrometry and tandem mass spectrometry (LC/MS and LC/MS/MS) is reported, Full-scan i onspray mass spectra of YTX, as acquired in single MS negative ion mod e by flow injection analysis (FIA), showed the most intense ion at mit 1141, assigned to the [M-2Na+H](-), the ion at mit 1163, assigned to the [M-Na](-) and a signal at mit 1185, due to the deprotonated molecu le [M-H](-) of the analyte taken here to be the disodium salt. Collisi on induced dissociation of the precursor ion at mit 1141., as obtained by FLA negative tandem mass spectrometry experiments, showed the most intense fragment ions in the higher mass region, at mit 1061, mit 924 , mit 855, mit 713, which are characteristic of the structure of the a nalyte, Ionspray reversed phase LC/MS and LC/MS/MS was performed by is ocratic elution at 30 mu L/min, with a mobile phase of acetonitrile-am monium acetate 4 mM, 80:20 (v/v), using a 1.0 mm i.d. C-18 column. The detection of YTX in Italian shellfish samples collected in 1997 from the Adriatic sea was successfully carried out using this method, permi tting demonstration of a false negative result obtained by the officia l mouse bioassay during routine control monitoring. (C) 1998 John Wile y & Sons, Ltd.