RATIONALEA　method　has　been　developed　for　simultaneous　determination　of　the　toxins　OA,　DTX-1,　AZA-1,　AZA-2　and　AZA-3　in　various　aquatic　products　as　these　can　cause　diarrhoetic　shellfish　poisoning　(DSP)　in　humans,　an　intoxication　characterized　by　vomiting　and　diarrhea.　METHODSSeparation　of　the　toxins　was　achieved　on　a　C18　column　(150mmx2.1mm,　3.5　mu　m)　using　an　acetonitrile/water　gradient　with　formic　acid　as　an　eluent　modifier.　Electrospray　ionisation　(ESI)　in　negative　mode　was　used　to　generate　the　molecule　related　ion　[M-H]-,　for　OA　and　DTX-1,　while　ESI　in　positive　mode　was　used　to　generate　the　molecule　related　ion　[M+H]+　for　AZAs.　Samples　were　extracted　with　80%　methanol,　followed　by　partitioning　with　ethyl　acetate,　purified　on　a　Poly-Sery　MAX　cartridge　and　finally　analyzed　by　LC/ESI-MS/MS　in　the　multiple　reaction　monitoring　(MRM)　mode.　RESULTSThe　limit　of　detection　(LOD)　and　limit　of　qualification　(LOQ)　of　the　method　were　in　the　range　of　0.02-0.79　mu　g/kg　and　0.07-2.64　mu　g/kg　in　Scomberomorus　niphonius,　blood　clam　and　oyster,　respectively,　recoveries　of　the　toxins　at　three　fortification　levels　ranged　from　71.3%　to　104.8%　with　relative　standard　deviation　from　1.0%　to　12.5%.　The　calibration　curves　were　well　linear　between　the　LC　peak　area　of　the　selected　ion　pair　and　the　concentration　of　the　toxins,　with　the　correlation　coefficient　over　0.99.　CONCLUSIONSThe　method　was　sufficiently　sensitive　to　permit　the　determination　of　the　toxins　DSP　and　AZA　in　sea　food.　Copyright　(c)　2014　John　Wiley　&　Sons,　Ltd.