TRACE·DETERMINATION OF DOMOIC ACID IN SEAWATER AND PHYTOPLANKTON BY HIGH­ PERFORMANCE LIQUID CHROMATOGRAPHY OF THE FLUORENYLMETHOXYCARBONYL (FMOC) DERIVATIVE*

A method is presented for the trace determination of domoic acid, a neurotoxic amino acid responsible for cases of Amnesic Shellfish Poisoning resulting from the consumption of contaminated shellfish. The method involves pre-column derivatization with 9-fluorenylmethylchloroformate to form the FMOC derivative followed by reversed-phase HPLC with fluorescence detection. The detection limit for domoic acid in seawater and aqueous extracts is 15pg/mL (50pM) using gradient elution, a 20/lL injection volume, and a 2.1mm I.D. microbore column. Use of dihydrokainic acid as an internal standard improved quantitation. The method was applied to the detection of domoic acid in seawater, in phytoplankton cultures (Nitzschia pungens forma multiseries), and in natural mixed phytoplankton assemblages in estuarine waters.