A method was developed for the simultaneous determination of chloramphenicol (CAP), thiamphenicol (TAP), and florfenicol (FF) residues in animal tissues using gas chromatography/mass spectrometry (GC/MS) with chemical ionization source in negative mode. The homogenized samples were extracted with ethyl acetate and the extracts were partitioned with n-hexane to remove lipids. Further cleanup was performed on a florisil cartridge and the purified samples were derivatized with Sylon BFT [N, O-bis (trimethylsilyl) trifluoroacetamide (BSTFA)-trimethylchlorosilane (TMCS), 99: 1, v/v] in toluene. Meta-nitrochloramphenicol (m-CAP) was used as the internal standard for the determination. Selected ion monitoring (SIM) was used for detection, ions were chosen, respectively, for the monitoring at m/z 432, 466, 468, 470 for m-CAP, m/z 376, 378, 466, 468 for CAP, m/z 409, 411, 499, 501 for TAP, and m/z 339, 341, 429, 431 for FF. Quantitative ions were selected at m/z 466 for CAP and m-CAP, at m/z 339 for FF and at m/z 409 for TAP. The detection limits were 0.03 microg/kg for CAP, 0.2 microg/kg for FF and TAP. The correlation coefficients were above 0.99 for the calibration curves of the medicines. The linear ranges were 0.1 - 8.0 microg/kg for CAP and 0.2 - 4.0 microg/kg for FF and TAP. The reproducibilities of the compounds within a batch were 5.5%, 10.4%, and 8.8% for CAP, FF, and TAP respectively, while the corresponding values between the batches were 7.4%, 20.7%, and 19.1%. The recoveries were 80.0% - 111.5%, and the relative standard deviations were 1.2% - 15.4%. The method is applicable for detection of the residues in animal derived food, such as pork, poultry and aquatic products.
