Abstract: A method for determination of enrofloxacin and ciprofloxacin residues in chicken eggs was developed using high-performance liquid chromatography coupled with tandem mass spectrometry （HPLC-MS/MS）. After extraction by 1% acetic acid in acetonitrile and purified by hexane, the samples were analyzed by the established HPLC-MS/MS method. The calibration curves of enrofloxacin and ciprofloxacin were linear in the range of 0.5-500 ng/mL （r ≥ 0.999）; the recoveries of enrofloxacin in chicken eggs ranged from 87.7% to 99.1%, and those of ciprofloxacin in the samples ranged from 89.1% to 101.4%; the limit of detection and the limit of quantification of the established HPLC-MS/MS method for enrofloxacin and ciprofloxacin were 0.5 μg/kg and 1.0 μg/kg, respectively. The residues and elimination regularity of enrofloxacin and its metabolite ciprofloxacin in chicken eggs were preliminarily revealed by using a HPLC-MS/MS based method the enrofloxacin and its metabolite were accumulated rapidly in eggs after the chicken were administrated, the metabolism of trace enrofloxacin was slow after 8 days of drug discontinuation, and the metabolism of enrofloxacin was complete after 25 days of drug discontinuation.

Key words: enrofloxacin, ciprofloxacin, chicken eggs, HPLC-MS/MS