Further studies on the analysis of DSP toxin profiles in Galician mussels

Further studies on mussel samples from Galicia, Spain, have revealed the pr esence of okadaic acid (OA), dinophysistoxin 2 (DTX2), and the fatty acid a cyl esters of both of these toxins as the "DTX3" complex. Measurements were performed with an improved in situ method for the formation of 9-anthryldi azomethane (ADAM) derivatives followed by liquid chromatography with fluore scence detection. Base hydrolysis of DTX3 toxins gave free OA and DTX2, whi ch were determined following ADAM derivatization. Results were confirmed by liquid chromatography/mass spectrometry analyses, and in most of the sampl es, free DTX2 was the most abundant toxin. However, the OA/DTX2 ratio in th e DTX3 conjugated form was different, with OA being the most abundant in al l cases. This difference could be due to different rates of metabolism of O A and DTX2 to the acyl esters or due to contamination of the shellfish by t he two toxins at different points in time, resulting in less acyl ester for mation for one toxin versus the other. The second possibility would be reas onable if two different source organisms were producing the toxins.