Analysis of Diarrhetic Shellfish Toxins (Okadaic Acid Group) Using Triple Quadrupole LC/MS/MS

Introduction

In regard to the handling of shellfish containing diarrhetic shellfish toxins, an instrumental analysis method is introduced based on "Handling of Shellfish Contaminated with Paralytic Shellfish Toxins, etc.", (Notice 0306 No. 2, dated March 6, 2015, issued by the Food Safety Manager, Pharmaceutical and Food Safety Bureau, MHLW). A regulatory value of 0.16 mg OA equivalent/kg has been set for the okadaic acid (abbreviated as OA) group, and selling shellfish that exceed the regulatory value is prohibited under the provisions of Chapter 6, Article 2 of the Food Sanitation Act. Since April 2016, it has been possible to reliably obtain certified reference materials produced domestically in Japan. Accordingly, the mouse toxicity test in Notice No. 37 "Testing for Diarrhetic Shellfish Toxins (Okadaic Acid Group)" dated May 19, 1981 was superseded as of April 1, 2017 by Notice 0308 No. 2 and Notice 0308 No. 9 "Partial Revision of " dated March 8, 2017. In this revision, a regulatory value for the OA group, which is recognized as toxic to humans, was introduced and this group has become targeted in an instrumental analysis method. On the other hand, the PTX and YTX groups, which do not cause diarrhea, are not covered by the instrumental analysis method. In addition to OA, which is a toxin produced by phytoplankton, the OA group includes the dinophysistoxin group (DTX1, DTX2 and DTX3) as similar compounds. Because each of these compounds has a different strength of toxicity, the toxicity of each compound is calculated by converting it into an equivalent toxicity in terms of OA. For this purpose, a toxicity equivalence coefficient (TEF) has been defined, and with OA set as 1, DTX1 is 1 and DTX2 is 0.5. OA, DTX1, and DTX2 quantitative results are converted to OA equivalent values by multiplying them by their respective TEF values, then the sum is calculated. DTX3 is an esterified compound with a fatty acid compound, which is a metabolite of scallops, and no TEF value is set for it because it is converted to OA, DTX1 or DTX2 by the hydrolysis process in the pretreatment operation. In this paper, we introduce an instrumental analysis method (LC/MS/MS) for the OA group.

October 24, 2019 GMT