DETERMINATION OF MILOXACIN AND ITS METABOLITE IN FISH BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH FLUORESCENCE AND UV DETECTION

A simple and rapid method for the determination of miloxacin (MLX) and its principal metabolite, 5,8-dihydro-8-oxo-1,3-dioxolo [4,5-g]quinoline-7-carboxylic acid (M-1), in cultured fish by high performance liquid chromatography (HPLC) with fluorescence and UV detection was developed. The drugs were extracted from fish with 0.2% metaphosphoric acid-methanol (7:3), followed by the Bond Elut C18 clean-up procedure. The HPLC separation was carried out on a L-column ODS (15 cm x 4.6 mm i.d.) using 0.05M sodium dihydrogenphosphate (pH 4.5)-acetonitrile (65:35) as the mobile phase at a flow-rate of 0.5 ml/min. The calibration graphs were rectilinear from 1 to 50 ng for MLX and M-1. The recoveries of MLX and M-1 from various fishes fortified at 0.5-mu-g/g were 84.5-87.9 and 74.8-77.6 %, respectively, with a coefficient of variation of 1.1-2.8 and 1.8-3.2%, respectively. The limits of detection were 0.01-mu-g/g for both drugs.