A multiresidue method was developed for the determination of fluoroquinolon
es 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 mi
crodialysis, concentrated on a trace enrichment column, and separated by re
versed-phase liquid chromatography with fluorescence detection. Norfloxacin
(NOR), ciprofloxacin (CIP), and sarafloxacin (SAR) were extracted from for
tified eggs over a range of 2-200 mug/kg, with recoveries of 65.7-78.9%, 65
.6-77.1%, and 67.6-110%, respectively. Enrofloxacin (ENRO) was extracted ov
er a range of 1-100 mug/kg, with recoveries of 71.5-86.7%, whereas desethyl
ene ciprofloxacin (DCIP) and danofloxacin (DANO) were extracted over a rang
e of 0.2-20 mug/kg, with recoveries of 68.7-90.7% and 76.0-93.8%, respectiv
ely. The limits of quantitation for the 6 fluoroquinolones were as follows:
DCIP and DaNO, 0.3 mug/kg; ENRO, 1 mug/kg; NOR and CIP, 2 mug/kg; and SAR,
3 mug/kg. Both SAR and ENRO incurred eggs were also successfully analyzed
using this method.