Simultaneous determination of enrofloxacin and its primary metabolite, ciprofloxacin, in chicken tissues

An HPLC method with fluorescence detection is presented for the analysis of enrofloxcin (ENR) and ciprofloxacin (CIP) in chicken tissue using sarafloxacin (SAR) as internal standard. Tissue sample preparations were carried out by adding a phosphate buffer (pH 7.4, 0.1 M), followed by extraction with trichloromethane. Fluoroquinolones were separated on a reversed-phase column with a mobile phase of aqueous phosphate buffer-acetonitrile (80:20). The concentrations of CIP, ENR and SAR eluted off the column, with retention times of 2.28, 3.30 and 4.40, respectively, were monitored by fluorescence detection at lambda (ex) 338 and lambda (em) 425 nm. The detection limit was 32 ng g(-1) for CIP and 10 ng g(-1) for ENR. The standard curves were linearly related to concentration in the range of 1 to 2000 ng g(-1). Recovery was determinated as 91.3% and 78.3% for ENR and CIP, respectively. The measurement of the tissue levels of ENR and CIP in the chicken after oral administration confirmed the utility of the proposed analytical methodology.