Abstract: [Objective]A method for the determination of chloramphenicol,thiamphenicol and florfenicol residues in sheep milk powder by liquid chromatography-tandem mass spectrometry was studied.[Method]The samples were extracted by acetonitrile,purified by solid phase extraction column,and analyzed qualitatively and quantitatively by internal standard method with methanol and water as mobile phase.[Result]The correlation coefficients of chloramphenicol,thiamphenicol and florfenicol were greater than 0.999,the detection limit of chloramphenicol was 0.1 µg/kg,and the detection limit of thiamphenicol and florfenicol was 0.2 µg/kg.The recovery rate of chloramphenicol was 100.9%~116.2%,the recovery rate of thifomycin was 88.4%~99.6%,and the recovery rate of florfenicol was 89.6%~103.2%.[Conclusion]The method has high sensitivity and accuracy,and is suitable for the determination of chloramphenicol,thiamphenicol and florfenicol residues in sheep milk powder.

Key words: liquid chromatography-tandem mass spectrometry, chloramphenicol, thiamphenicol, flufenicol, sheep milk powder