DETERMINATION OF PECTENOTOXIN-2 AFTER SOLID-PHASE EXTRACTION FROM SEAWATER AND FROM THE DINOFLAGELLATE DINOPHYSIS-FORTII BY LIQUID-CHROMATOGRAPHY WITH ELECTROSPRAY MASS-SPECTROMETRY AND ULTRAVIOLET DETECTION -EVIDENCE OF OXIDATION OF PECTENOTOXIN-2 TO PECTENOTOXIN-6 IN SCALLOPS

Solid-phase extraction of pectenotoxin-2 (PTX2) and pectenotoxin-6 (PT X6) from seawater samples using a nonpolar cartridge column Sep-Pak C- 18 was investigated for determination of PTXs in toxic phytoplankton. PTX2 and PTX6 were almost completely recovered from the seawater sampl es. Determinations of PTX2 from the toxic phytoplankton and scallops w ere carried out by Liquid chromatography (LC) on UV trace equipped wit h an atmospheric pressure electrospray ionization mass spectrometry (E SI-MS). PTX2 obtained from the toxic phytoplankton and scallops yielde d a mass spectra exhibiting abundant [M+H](+), [M+NH4](+) and [M+Na]() indicating that ESI-MS is useful for the identification of PTX2. Det erminations of PTX6 from the toxic phytoplankton and scallops were car ried out by LC fluorescence detection. A significantly higher content of PTX6 compared to PTX2 in scallops was observed, suggesting that a t ransformation of PTX2 to PTX6 in tissues of the scallops occurs rapidl y. (C) 1998 Elsevier Science B.V. All rights reserved.