Determination of okadaic acid content of dinoflagellate cells: a comparison of the HPLC-fluorescent method and two monoclonal antibody ELISA test kits.

Total okadaic acid (okadaic acid plus methylokadaic acid) in acclimated clones of the dinoflagellates Prorocentrum hoffmannianum and P. lima was determined using the HPLC-fluorescent method, UBE ELISA test kit, and Rougier ELISA test kit. The nonokadaic acid-producing species. Amphidinium klebsii, Prorocentrum mexicanum, P. micans, P. cassubicum, and Gambierdiscus toxicus were examined using the same methods of analysis. All three methods yielded consistent results for P. hoffmannianum which produces only okadaic acid. However, results of the three methods were not consistent for P. lima which produces both okadaic acid and methylokadaic acid. The UBE ELISA demonstrated little or no cross-reactivity with methylokadaic acid; whereas, the Rougier ELISA demonstrated varying degrees of cross-reactivity with that analog. Analyses of nonokadaic acid producing-species yielded negative results, with one exception. The Rougier ELISA demonstrated reactivity with extracts of G. toxicus. Since outbreaks of DSP may be caused by okadaic acid, methylokadaic acid, or a combination of these toxins, both ELISA kits may underestimate total toxin present in toxic shellfish.