Abstract: A simple and sensitive liquid chromatography method that allows for the determination of Fenbendazole and its metabolites（Fenbendazole Sulfone and Offendazole）in chicken was established. The chicken tissue samples were mashed, then added with anhydrous sodium sulfate, and then extracted with ethyl acetate containing dimethyl sulfoxide. The extract was defatted with hexane,and then purified by C₁₈ solid phase cartridge. The eluent was dried with nitrogen, and then dissolved with 0.5 mL mobile phase（acetonitrile∶5 mol/L ammonium acetate=1∶1）. The final extracts were analysed by HPLC. The mobile phase was acetonitrile and 5 mol/L ammonium acetate at a flow rate of 0.8 mL/min. The sample volume was 20 μL, the column temperature was room temperature, and the detection wavelength was 294 nm. The linear range was 0.02-0.50 μg/mL, R²>0.999. In the range of 1 -25 μg/kg, the average recoveries of the three materials were 77.9-98.6%, the intra day coefficient of variation was 3.10-6.81%（n=3）, and the inter day coefficient of variation was 1.19-7.74%（n=3）. The method is simple, sensitive, efficient, and suitable for the detection of fenbendazole and its metabolites in animal tissues.

Key words: Fenbendazole, Offendazole, Fenbendazole Sulfone, HPLC, residue detection