The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop cer tified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investiga te the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the cer tification exercise. Fifteen laboratories participated in this certificatio n study and were asked to measure saxitoxin and decarbamoylsaxitoxin in reh ydrated lyophilized mussel material and in a saxitoxin-enriched mussel mate rial. The participants were allowed to use a method of their choice but wit h an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbam oyl-saxitoxin. Most participants (13 of 15) were able to meet all the crite ria set for the certification study. Results for saxitoxin. 2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussel s. Results obtained for decarbamoylsaxitoxin. 2HCl yielded a certified mass fraction of 1.59<plus/minus>0.20 mg/kg. The results for saxitoxin. 2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/-0.06 mg /kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laborator ies to test their method for accuracy and performance.