SCREENING FOR OKADAIC ACID BY IMMUNOASSAY

Increasing incidences of phytoplankton blooms with the potential dange r of toxin release into the food chain have necessitated the search fo r new diagnostic methods that can detect toxins quickly and reliably. A competitive enzyme-linked immunosorbent assay (ELISA) was developed to quantitate okadaic acid in shellfish and phytoplankton extracts. To determine the specificity of the assay, a number of toxins, such as c alyculin A, brevetoxin-l,and dinophysistoxins-1, -2, and -3 were analy zed. Both dinophysistoxins-2 and -1 could be detected by the assay but in concentration ranges 10- and 20-fold higher than that for okadaic acid, respectively. Dinophysistoxin-3, calyculin A, or brevetoxin-1 co uld not be detected with this assay. To validate the accuracy of the m ethod, 18 mussel and 7 phytoplankton extracts were analyzed in paralle l for okadaic acid content by ELISA and liquid chromatography combined with either fluorescence or mass spectrometric detection. Very high c orrelation between the results was found.