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 certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate 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 certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-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 laboratories to test their method for accuracy and performance.     

连云港海州湾麻痹性贝类毒素中毒分析

为分析连云港地区麻痹性贝类毒素中毒特征,对连云港海州湾织纹螺进行形态鉴定,收集近年麻痹性贝类中毒资料,应用小白鼠生物测定法检测螺肉中麻痹性贝类毒素。结果连云港海州湾存有4种织纹螺,其中以半褶织纹螺含麻痹性贝类毒素量高(1.6×103μg100g螺肉),并导致连云港地区10起、银川1起麻痹性贝类中毒;1992年还发生一起由泥螺引起的麻痹性贝类中毒。中毒者均表现为下行性神经麻痹症状,重者致死。鉴于海洋污染的严重性,为保障海洋贝类的食用安全,应对贝类进行毒素等安全指标的监测。     

Measurement of paralytic shellfish toxins in molluscan extracts: comparison of the microtitre plate saxiphilin and sodium channel radioreceptor assays with mouse bioassay, HPLC analysis and a commercially available cell culture assay

This study compared five methods of measuring paralytic shellfish toxins (PSTs) including the long-used mouse lethality bioassay, a commercially available cell culture test (MIST ® Quantification kit), HPLC analysis, and two newly developed radioreceptor assays utilizing mammalian sodium channels and saxiphilin. Methods were challenged with toxic shellfish extracts prepared according to the AOAC official method. The best correlations between predicted toxicity values being 0.9 or better, were those between HPLC analysis when compared with both radioreceptor assays and the mouse lethality bioassay, as well as that between the saxiphilin and the sodium channel radioreceptor assays. In all cases, statistically significant correlations existed between the toxicity measurements of the same extracts. The ratios between some methods were not unitary as measured by the slopes of the regression lines used for correlation analyses. HPLC analysis predicted more toxicity than all of the bioassays. The saxiphilin assay underestimated toxicity relative to the mouse bioassay, the MIST ® kit determinations and the sodium channel assay. The sodium channel assay predicted there to be less toxicity than the mouse bioassay and the MIST ® kit. Of all of the techniques used, the MIST ® kit correlation with the mouse bioassay was nearest to one. Each method possesses different virtues and it may be that a multi-method approach would harness the benefits of each method for various aspects of a shellfish testing regime.