Abstract: To established a method to detect the residues of clenbuterol,salbutamol and ractopamine in pork by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and optimized it. The samples was treated by 0.2 mol/L ammonium acetate buffer and added the beta-glucuronidase to it,purified the extracting solution with PCX column,determined by LC-MS/MS and quantitated with internal standard method. The results showed that the residual concentration of the three kinds of β-agonists in pork was 0.2 to 10.0 μg/kg and the linear correlation was well. The linear correlation coefficient were 0.9997,0.9999 and 0.9993,respectively. We detected the limitative concentration was 0. 5 μg/kg and the coefficient of recovery were 93.57% to 96.63%,92.35% to 96.01% and 91.66% to 96.54%,respectively. This method has the advantages of good sensitive,accuracy and easy repetition and it is suitable for the detection of clenbuterol,salbutamol and ractopamine in pork.

Key words: LC/MS/MS; pork; clenbuterol; sabutamol; ractopamine