A collaborative study was conducted for the determination of paralytic shellfish poisoning (PSP) toxins in shellfish. The method used liquid chromatography with fluorescence detection after prechromatographic oxidation of the toxins with hydrogen peroxide and periodate. The PSP toxins studied were saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins 2 and 3 (GTX2,3; together), gonyautoxins 1 and 4 (GTX1,4; together), decarbamoyl saxitoxin (dcSTX), B-1 (GTX5), C-1 and C-2 (C1,2; together), and C-3 and C-4 (C3,4; together). B-2 (GTX6) toxin was also included, but for qualitative identification only. Mussels, both blank and naturally contaminated, were mixed and homogenized to provide a variety of PSP toxin mixtures and concentration levels. The same procedure was followed with clams, oysters, and scallops. Twenty-one test samples in total were sent to 21 collaborators who agreed to participate in the study. Results were obtained from 18 laboratories representing 14 different countries. It is recommended that the method be adopted First Action by AOAC INTERNATIONAL.

Alexandrium is detected throughout Scottish coastal waters on a near annual basis, and corresponding paralytic shellfish poisoning (PSP) toxins are found in Scottish shellfish. Previous studies at selected Scottish sites have shown diversity within the genus Alexandrium. In order to examine the distribution, diversity and toxicity of Alexandrium populations around the Scottish coast, historic cyst and cell data were compiled and cultures established from sediment and water samples. Historic data showed high cell densities of Alexandrium in Shetland, Orkney, the Western Isles and mainland east coast. Low abundances of Alexandrium cysts were observed along the west coast. Four species of Alexandrium (A. tamarense, A. ostenfeldii, A. minutum and A. tamutum) were established in laboratory culture and identified using morphological criteria. Sequencing of LSU rDNA from isolates of A. ostenfeldii, A. minutum and A. tamutum confirmed their identification and showed them to be similar to other European strains. Alexandrium tamarense, identified by morphological criteria, was observed to have a widespread distribution around the coast. Both toxin-and non toxin-producing strains of this species were isolated, suggesting the presence of A. tamarense Groups I and III. Alexandrium ostenfeldii was isolated from the east coast and Shetland Isles and was observed to produce both spirolide and PSP toxins. Alexandrium tamutum was identified from cultures isolated from Shetland and Orkney, the most northerly observation of this species to date. PSP toxins were not detected in isolates of A. minutum from the east coast and Orkney or of A. tamutum under the culture conditions used. This study has highlighted the diversity of Alexandrium in Scottish waters and reveals the requirement for temporal and regional studies on a species level in order to understand the variation in cell densities and PSP toxicity that is observed on an annual and decadal scale.

No abstract

Contamination of shellfish with paralytic shellfish poisoning (PSP) toxins produced by Alexandrium species poses a potential threat to the sustainability of the Scottish aquaculture industry. Routine LM analysis of water samples from around the Scottish coast has previously identified Alexandrium (Dinophyceae) as a regular part of the spring and summer phytoplankton communities in Scottish coastal waters. In this study, Alexandrium tamarense (M. Lebour) Balech isolated from sediment and water samples was established in laboratory culture. Species identification of these isolates was confirmed using thecal plate dissections and by molecular characterization based on their LSU and, in some cases, ITS rDNA sequence. Molecular characterization and phylogenetic analysis showed the presence of two ribotypes of A. tamarense: Group I (North American ribotype) and Group III (Western European ribotype). Assessment of PSP toxin production using hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) showed that A. tamarense Group I produced a complex array of toxins (∼2,000 fg STX equivalents · cell(-1) ) with the major toxins being C2, neosaxitoxin (NEO), saxitoxin (STX), gonyautoxin-4 (GTX-4), and GTX-3, while A. tamarense Group III did not produce toxins. Historically, it was considered that all Alexandrium species occurring in Scottish waters produce potent PSP toxins. This study has highlighted the presence of both PSP toxin-producing and benign species of A. tamarense and questions the ecological significance of this finding.

No abstract

An interlaboratory study was conducted for the determination of paralytic shellfish poisoning (PSP) toxins in shellfish. The method used liquid chromatography with fluorescence detection after prechromatographic oxidation of the toxins with hydrogen peroxide and periodate. The PSP toxins studied were saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins 2 and 3 (GTX2,3 together), gonyautoxins 1 and 4 (GTX1,4 together), decarbamoyl saxitoxin (dcSTX), B-1 (GTX5), C-1 and C-2 (C1,2 together), and C-3 and C-4 (C3,4 together). B-2 (GTX6) toxin was also included, but for qualitative identification only. Samples of mussels, both blank and naturally contaminated, were mixed and homogenized to provide a variety of PSP toxin mixtures and concentration levels. The same procedure was followed with samples of clams, oysters, and scallops. Twenty-one samples in total were sent to 21 collaborators who agreed to participate in the study. Results were obtained from 18 laboratories representing 14 different countries.

No abstract

A rapid multiple toxin method based on liquid chromatography with mass spectrometry (LC/MS) was developed for the detection of okadaic acid (OA), dinophysistoxin-1 (DTX-1), DTX-2, yessotoxin (YTX), homoYTX, 45-hydroxy-YTX, 45-hydroxyhomo-YTX, pectenotoxin-1 (PTX-1), PTX-2, azaspiracid-1 (AZA-1), AZA-2, and AZA-3. Toxins were extracted from shellfish using methanol–water (80%, v/v) and were analyzed using a C8 reversed-phase column with a 5 mM ammonium acetate–acetonitrile mobile phase under gradient conditions. The method was validated for the quantitative detection of OA, YTX, PTX-2, and AZA-1 in 4 species (mussels, Mytilus edulis; cockles, Cerastoderma edule; oysters, Crassostrea gigas; king scallop, Pecten maximus) of shellfish obtained from United Kingdom (UK) waters. Matrix interferences in the determination of the toxins in these species were investigated. The validated linear range of the method was 13–250 μg/kg for OA, PTX-2, and AZA-1 and 100–400 μg/kg for YTX. Recovery and precision ranged between 72–120 and 1–22%, respectively, over a fortification range of 40–160 μg/kg for OA, PTX-2, and AZA-1 and 100–400 μg/kg for YTX. The limit of detection, reproducibility, and repeatability of analysis showed acceptable performance characteristics. A further LC/MS method using an alkaline hydrolysis step was assessed for the detection of OA, DTX-1, and DTX-2 on their esterified forms. In combination with the LC/MS multiple toxin method, this allows detection of all toxin groups described in Commission Decision 2002/225/EC.