ABSTRACT
Domoic acid (DA) is a potent neurotoxic amino acid which has been established as the agent responsible for amnesic shellfish poisoning (ASP). Beginning in the fall of 1991, DA was discovered in anchovies, razor clams and Dungeness crabs harvested from the west coast of the United States. A surveillance program for DA in shellfish was initiated by the responsible regulatory agencies which successfully managed the situation. Routine determination of DA is accomplished using FIPLC with ultraviolet (UV) detection. In the present study we describe a complementary method for confirmation of DA in shellfish. In the method, DA is isolated from crude methanol/water tissue extracts by solid phase extraction using a strong cation exchange column. Conversion of DA into the corresponding volatile N-formyl-O-methyl derivative is accomplished in a single reaction step by treatment with dimethylformamide dimethyl acetal. The resulting derivative can be analyzed by gas chromatography/mass spectrometry (GC/MS) using widely available bench-top instrumentation. The derivative of DA affords a mass spectrum with several diagnostic ions useful for selected ion monitoring. The method can confirm DA in razor clam, blue mussels, and Dungeness crab tissues to below the current regulatory action levels.
