After homogenization, the sample was extracted with 1% trichloroacetic acid solution, and then cleaned with OASIS MCX LP extraction column. The extracted solution was concentrated at low-pressure and dissolved with methanol. Liquid chromatog. tandem mass spectrometry (LC-MS-MS) anal. was performed on a Waters BEH-C8 column, acetonitrile and water were used as mobile phase. The linear ranges were from 0.1 mg/kg to 10.0 mg/kg with correlation coefficient of 0.9999. The mean recoveries were from 71% to 95%, and the RSD was 4.56%-9.82% (n=6). The limit of determination was 0.5 mg/kg.