Rapid screening fluorescence method applied to detection and quantitation of paralytic shellfish toxins in invertebrate marine vectors

Abstract

ABSTRACTA rapid screening method is described for the determination of paralytic shellfish toxins (PST), in fresh marine vectors (bivalves and gastropods), at levels ranging from 0.05 to 5.0 mg STX-eq kg−1. PST are extracted from marine vector homogenates with acetic acid according to the Pre-COX-LC-FLD method. At the same time, the obtained extract is oxidised simultaneously in hydrogen peroxide and periodate oxidate to determine PST, non-N-hydroxylated and N-hydroxylated toxins, respectively. Then, they are analysed using a microplate fluorometer (Ex: 335 nm/Em: 405 nm). All the samples were compared with the liquid chromatography post-column oxidation method. Recoveries of PST added to fresh and processed marine vectors averaged 93.9% with a coefficient of variation of 6.1%. Both methods showed a good linear regression (r2 = 0.97). The method shows good intra- and inter-day precisions with a relative coefficient of variation of ≈ 3.8% and 5.7%, respectively. The limit of quantification of the rapid screening fluorescence method was ≈ 0.082 mg STX-eq kg−1, with ≤5% false positives. The established rapid screening fluorescence methods offer highly effective and verifiable pre-analyses of PST contamination in marine vectors and can be used for routine screening of the PST in seafood before formal identification by confirmatory methods (Pre-COX LC-FLD method, Lawrence method).