Direct identification of yessotoxin in shellfish by liquid chromatography coupled with mass spectrometry and tandem mass spectrometry

Abstract

A new method for the direct identification of yessotoxin (YTX), a polyether compound belonging to the diarrhoeic shellfish poisoning (DSP) toxins, using liquid chromatography coupled with mass spectrometry and tandem mass spectrometry (LC/MS and LC/MS/MS) is reported. Full-scan ionspray mass spectra of YTX, as acquired in single MS negative ion mode by flow injection analysis (FIA), showed the most intense ion at m/z 1141, assigned to the [M−2Na+H]−, the ion at m/z 1163, assigned to the [M−Na]− and a signal at m/z 1185, due to the deprotonated molecule [M−H]− of the analyte taken here to be the disodium salt. Collision induced dissociation of the precursor ion at m/z 1141, as obtained by FIA negative tandem mass spectrometry experiments, showed the most intense fragment ions in the higher mass region, at m/z 1061, m/z 924, m/z 855, m/z 713, which are characteristic of the structure of the analyte. Ionspray reversed phase LC/MS and LC/MS/MS was performed by isocratic elution at 30 μL/min, with a mobile phase of acetonitrile–ammonium acetate 4 mM, 80:20 (v/v), using a 1.0 mm i.d. C18 column. The detection of YTX in Italian shellfish samples collected in 1997 from the Adriatic sea was successfully carried out using this method, permitting demonstration of a false negative result obtained by the official mouse bioassay during routine control monitoring. © 1998 John Wiley & Sons, Ltd.