New approach to the direct detection of known and new diarrhoeic shellfishtoxins in mussels and phytoplankton by liquid chromatography-mass spectrometry

A new approach using combined liquid chromatography-mass spectrometry (LC-M S) with ionspray ionization is proposed for the direct detection of known a nd new toxins in mussels and phytoplankton. A first stage reversed-phase, n egative ion mode, selected ion monitoring (SIM) LC-MS analysis was performe d in order to detect DSP toxins in the same chromatographic run with a tota l run time of 20 min. The toxins analysed included yessotoxin (YTX), okadai c acid (OA) and four of its analogues, dinophysistoxins (i.e. DTX-1, DTX-2, DTX-2B, DTX-2C), and pectenotoxins (PTXs), involving PTX-2, two PTX-2 seco acids (PTX-2SAs), PTX-2SA, 7-epi-PTX-2SA, and AC1, the three isomeric toxin s structurally related to PTX-2 recently identified in Irish phytoplankton. Positive samples can, therefore, be analyzed through reversed-phase, posit ive ion mode SIM LC-MS, in order to perform complete chromatographic separa tions of the structurally related toxins within the OA and PTX groups. Deta iled toxin profiles of a number of toxic phytoplankton and shellfish, from different marine areas, were easily obtained through the new approach. PTX- 2SAs and AC1 were found in phytoplankton and shellfish from Ireland as well as in Italian shellfish. Moreover, for the first time there was evidence o f the presence of PTX-2 in Irish phytoplankton. YTX was present in Italian shellfish. Four isomeric OA toxins were detected in samples from Ireland wi th OA, DTX-2 and DTX-2B present in shellfish, and OA, DTX-2 and DTX-2C in p hytoplankton. In contrast, OA was the only toxin from this group to be dete cted in Italian mussels. (C) 1999 Elsevier Science B.V. All rights reserved .