Multiresidue determination of fluoroquinolones in eggs

A multiresidue method was developed for the determination of fluoroquinolones in eggs. Extraction of eggs with ammoniacal acetonitrile was followed by liquid-liquid defatting, solvent evaporation, and redissolution in a small volume of buffer. The fluoroquinolones were further purified by on-line microdialysis, concentrated on a trace enrichment column, and separated by reversed-phase liquid chromatography with fluorescence detection. Norfloxacin (NOR), ciprofloxacin (CIP), and sarafloxacin (SAR) were extracted from fortified eggs over a range of 2-200 microg/kg, with recoveries of 65.7-78.9%, 65.6-77.1%, and 67.6-110%, respectively. Enrofloxacin (ENRO) was extracted over a range of 1-100 microg/kg, with recoveries of 71.5-86.7%, whereas desethylene ciprofloxacin (DCIP) and danofloxacin (DANO) were extracted over a range of 0.2-20 microg/kg, with recoveries of 68.7-90.7% and 76.0-93.8%, respectively. The limits of quantitation for the 6 fluoroquinolones were as follows: DCIP and DANO, 0.3 microg/kg; ENRO, 1 microg/kg; NOR and CIP, 2 microg/kg; and SAR, 3 microg/kg. Both SAR and ENRO incurred eggs were also successfully analyzed using this method.