Determination of flumequine and oxolinic acid in fortified chicken tissue using on-line dialysis and high-performance liquid chromatography with fluorescence detection

Isolation of the fluoroquinolones, flumequine and oxolinic acid, from fortified chicken liver was achieved using liquid-liquid extraction, aqueous on-line dialysis and trace enrichment. Dialysis, trace enrichment and column switching were performed using the ASTED system. Separation of the isolated compounds in the tissue extracts was performed using reversed-phase HPLC and fluorescence detection. This procedure yielded excellent mean recoveries at the 50, 25, 10 and 5 ng/g spiking levels for flumequine (94-96%; 4-9% R.S.D.) and at the 25 and 5 ng/g spiking levels for oxolinic acid (98-99%; 4-6% R.S.D.). Clean chromatograms were obtained, allowing detection of 5 ng/g flumequine and 2.5 ng/g oxolinic acid to be easily made. Due to its lower organic solvent consumption, automation and on-line capabilities, this method may be a suitable replacement for conventional chemical extraction techniques for drug residues in animal tissues. (C) 1998 Elsevier Science B.V.