Abstract:  The residual veterinary drug of ractopamine in the animal tissues was extracted and purified by the method of liquid-liquid partition and solid phase extraction.The ractopamine was separated and assayed by gas chromatography spectrometry(according to the selected ion mode,the selected ions were:m/z163,m/z192,m/z234,m/z250)after derivatization of the purified sample with the TMS derivative reagent of BSTFA,and the qualitative and quantitative analysis methods were developed.Its limit of detection is 0.5μg/L,and there is a good linear correlationship between the ratio of peak areas and the concentration ofractopamine in the range of 1～1000μg/L.The correlative coefficient is 0.9998,the recoveries of different concentration of ractopamine in different tissues are:liver 70.2%～75.4%,fat 71.2%～84.7%,kidney 72.8%～80.9% and meat 75.2%～86.4%,respectively.The RSD of the method is between 1.8% and 5.6%.

Key words:  , solid phase extraction； gas chromatography-mass spectrometry； ractopamine； selected ion monitoring；