Determination of fluoroquinolone residues in animal tissues by liquid chromatography

A simple liquid chromatographic (LC) method was developed for the determination of fluoroquinolones (ciprofloxacin, difloxacin, enrofloxacin and sarafloxacin) in animal tissues. Isolation of fluoroquinolones from biological matrices was performed with 5% trichloroacetic acid-acetonitrile (7:3) solution. For clean-up, solid-phase extraction with an SDBI (styrene-divinylobenzene) cartridge was used. LC analyses were performed with analytical column (LiChrospher 100 RP-8 5 microns) and mobile phase (0.025 M o-phosphoric acid-acetonitrile 70:30, v/v) in ion-pair mode. The whole procedure was validated in intra- and inter-assay reproducibility and accuracy determination by simultaneously assaying of muscle, liver and kidney samples supplemented with fluoroquinolones at the level of 30 and 60 ng/g, respectively. The statistical evaluation demonstrates high absolute recovery (> 80%) and low coefficient of variation (< 10%) for all analysed samples. The detection limits for fluoroquinolones were 5 ng/g in muscle, liver and kidney samples.