Development of an ultrasensitive immunoassay for rapid measurement of okadaic acid and its isomers

This report highlights the characteristics of an okadaic acid immunoassay w ith limits of detection in the subfemtomole range. Two different immunoassa y formats were investigated and their characteristics compared in relation to linear ranges, limits of detection, and cross-reactivity with other seaf ood toxins present in water and/or mussel samples. The developed ELISA syst em can be manipulated to quantitatively measure total diarrhetic shellfish poisoning (DSP) content or for okadaic acid and dinophysistoxin-1 individua l concentrations by variation of the format of the immunoassay. Real mussel samples were validated in percentage recovery test. Calibration curves wer e established, and aliquots of real samples were tested. Very good recoveri es were attained, highlighting the validity of the ELISA system to accurate ly determine the DSP concentration in mussel samples.