Abstract:A method for the determination of chloramphenicol and dexamethasone in chicken was developed using high performance liquid chromatography coupled tandem quadrupole linear ion trap mass spectrometry. The target analytes were extracted with ethyl acetate，and evaporated to dryness．The extracts were defatted with hexane and extracted by ethyl acetate again.chloramphenicol and dexamethasone were detected with electrospray ionization in both positive and negative modes using multiple reaction monitoring，and quantified by the internal standard method after separation through ZORBAX Eclipse Plus C18（1.7 μm，3.0 mm×100 mm）.With the optimal conditions，the calibration curves of chloramphenicol and dexamethasone were linear in the ranges of 0.10 ng/mL-40.0 ng/mL and 0.20 ng/mL-40.0 ng/mL，and correlation coefficients no less than 0.99.The limits of quantitation（LOQs）were 0.1μg/kg and 0.2μg/kg respectively.The average recoveries of chloramphenicol and dexamethasone were ranged from 93.6%to 102.2%and 90.3%to 95.8%respectively with both RSD not more than 5%．