A feasibility study into the provision of Paralytic Shellfish Toxins laboratory reference materials by mass culture of Alexandrium and shellfish feeding experiments

As the official control laboratory for biotoxin testing in England, Wales and Scotland, Cefas employs two approaches for the detection of Paralytic Shellfish Poisons (PSP) in bivalve shellfish: a qualitative HPLC method for oysters, whole king scallops and cockles (with PSP bioassay confirmation of positive HPLC samples) with subsequent quantitation of positive samples by mouse bioassay and a quantitative HPLC method for mussels (no PSP bioassay confirmation required). To aid the validation of the quantitative HPLC method for native oysters, Pacific oysters, cockles and king scallops and ultimately remove the need for the PSP bioassay for these species, appropriate contaminated shellfish matrices were required. As it was not possible to obtain naturally contaminated material for these species, shellfish were contaminated in-house through feeding experiments with high concentrations of Alexandrium species. A number of feeding experiments with two Alexandrium strains were performed successfully. The contaminated shellfish materials generated contained a number of different profiles of PSP toxins.This work has demonstrated the feasibility of these methods for the production of laboratory reference materials in a variety of bivalve shellfish species. Based on this study laboratory reference material production via these methods is now undertaken routinely within Cefas. By running two concurrent feeding trials per year for each species, enough laboratory reference material is produced for approximately 1 year of the programme. This removes the necessity for natural contaminated material which is not always available for reference material production. Additionally, such materials enable both the comparative testing of different PSP methodologies and the ongoing generation of long-term precision data for the HPLC method.