DETERMINATION OF SAXITOXIN BY LIQUID-CHROMATOGRAPHY THERMOSPRAY MASS-SPECTROMETRY

The determination of the paralytic shellfish Poison saxitoxin by liqui d chromatography/thermospray-mass spectrometry (LC/TS-MS) was investig ated. It was found that a commercial sample contained an impurity, whi ch was identified as the plasticizer tris(2-butoxyethyl) phosphate. Sp raying of saxitoxin in acid solution at pH 2 led to a useful TS mass s pectrum, containing some fragment ions in addition to the protonated m olecule. Using pentafluoropropionic acid as a counter-ion, saxitoxin c ould be determined by LC/TS-MS on a C18 reversed-phase column. By inje cting the relatively large volume of 1 mL a concentration of 30 ng/mL could be measured.