This European prestandard specifies a method for the quantitative determination of saxitoxin, dc-saxitoxin and the qualitative determination of neo-saxitoxin, and the gonyau toxins GTX-2 and GTX-3 in mussels. The method can also be used to identify the toxins C-1, C-2, GTX-5 and GTX-6 after hydrolysis and, if these toxins are present, to exclude false positive results for GTX-2, GTX-3, neo-saxitoxin and saxitoxin. For mussel the lowest limit of determination is for saxitoxin 0,04 mg/kg mussel meat and for dc-saxitoxin 0,03 mg/kg mussel meat (signal/noise = 10). The upper limits of determination have not been determined. The limits of detection for C-1, C-2, GTX-2, GTX-3, GTX-5, GTX-6 and neo-saxitoxin have not been determined. PSP (Paralytic Shellfish Poisoning) toxins are extracted from mussels homogenate with an acidic aqueous solution. After centrifugation the supernatant is purified by solid phase extraction (SPE) over a C18 clean-up cartridge. Part of the extract is directly injected on the HPLC for toxin determination. After the separation on the analytical column, post column derivatisation is used and the derivatized toxins are detected using fluorimetric detection. HPLC analysis is separated in 2 parts: a system to separate the saxitoxin group toxins (saxitoxin, dc-saxitoxin and neo-saxitoxin) and a system to separate the GTX group toxins (GTX-2 and GTX-3 ). Identification after hydrolysis is based on the transformation of the N-sulfo-carbamoyl toxins to their corresponding carbamate toxins detection.#,,#