Stable isotope dilution assay for the accurate determination of tricaine in fish samples by HPLC-MS-MS

Tricaine methanesulfonate is one of most commonly used anesthetics in fish during blood sampling, artificial propagation and long-distance transportation. In this study, an accurate method for the quantitative determination of tricaine in fish samples by a stable isotope dilution assay coupled with high-performance liquid chromatography-triple quadrupole mass spectrometry was developed. Tricaine-D₅ was synthesized and used as an isotopically labeled internal standard for the determination of tricaine. The analytical performance of the method was validated for tricaine determination in marine fish and freshwater fish. The determination of tricaine was linear in the range of 2.0-200.0 μg L^-1 . The limit of detection and limit of quantitation for fish muscle tissues were 1.0 and 4.0 μg kg^-1 , respectively. Good recoveries were obtained in the range of 92.08-97.50%. The inter- and intra-assay relative standard deviations (RSD values) were investigated, and the values were 0.39-3.01 and 0.85-2.77%, respectively. The values of CCα and CCβ were 10.21-10.43 and 10.42-10.87 μg kg^-1 , respectively. The clearance of MS-222 from grass carp was further studied using our method. The results demonstrate that MS-222 could be well absorbed and rapidly eliminated after bath administration.