Determination of 17 alpha-methyltestosterone in aquatic products using high-performance liquid chromatography-tandem mass spectrometry

17 alpha-methyltestosterone (MT) is widely used in aquaculture in order to increase harvest yield. However, illegal addition of MT is potentially toxic to human. A simple and rapid method for the determination of MT in aquatic products was established on HPLC-MS/MS. Sample preparation was optimized using simple liquid-liquid extraction techniques with ethyl acetate and n-hexane. The analyte was separated on Capcell PAK C18 MG II (100 mm x 2.0 mm, 5 mu m), with a solution of 0.1 % formic acid in water and acetonitrile, and analyzed with multiplereaction monitoring (MRM) mode on HPLC-MS/MS. Good linearity with high correlation coefficient (R2 >= 0.9997) was obtained between 2 and 200 mu g/L. The limits of detection (LODs) and quantitation (LOQs) were 0.4 and 1 mu g/kg respectively. Good recoveries were demonstrated between 86.4 and 104.6 %. The precisions of interday and intra-day were validated and the results indicated acceptable stability and reproducibility. The analyte showed stable up to 30 days storage at -20 degrees C. Samples purchased from Shanghai market for each matrix (shrimp, Chinese mitten crab, tilapia, eel, bullfrog and mussel) were tested for method application. In summary, the proposed method was validated for MT determination in aquatic products.