High-performance liquid chromatographic method with fluorescence detection for the screening and quantification of oxolinic acid, flumequine and sarafloxacin in fish

A previously published liquid chromatographic method for determining residues of nine quinolones in chicken, porcine, bovine and ovine muscle was adapted and applied to fish tissue for simultaneous determination of three quinolones (flumequine, oxolinic acid and sarafloxacin). The analytes were extracted from homogenised muscle using an acetonitrile basic solution. After centrifugation, partial evaporation and cleaning with hexane, direct injection was possible. Separation was achieved on PLRP-S column and detection was performed with a programmable fluorescence detector. Chromatographic conditions were optimised to be compatible with the determination of the three quinolones in a single run. The linearity, recovery, accuracy and precision of the method were evaluated from fortified tissue samples at concentration levels ranging from 15 to 120 μg kg−1 for sarafloxacin and 75 to 600 μg kg−1 for oxolinic acid and flumequine according to the EU maximum residue limit of each quinolone. The limits of detection were estimated to be 2, 5 and 7 μg kg−1, respectively, for sarafloxacin, oxolinic acid and flumequine. The limits of quantification were validated at 15 μg kg−1 for sarafloxacin and 75 μg kg−1 for oxolinic acid and flumequine. Mean extraction recoveries of quinolones in fish ranged from 56.9 to 71.0%. This simple and rapid method is suitable for residue control.