Liquid-chromatographic determination of sarafloxacin residues in channel catfish muscle-tissue

A liquid chromatographic method is described for the determination of sarafloxacin hydrochloride residues in channel catfish (Ictalurus punctatus) fillets. Sarafloxacin was extracted from fillet tissue with acetonitrile–water (1+1). The extract was centrifuged and the supernatant was partitioned with hexane. The aqueous fraction was filtered through a 0.45 μm filter and evaporated to dryness. The sample was redissolved with 20% acetonitrile–methanol (3 + 2) and 80% trifluoroacetic acid (0.1%), centrifuged, and filtered to remove proteins. Samples were analyzed by chromatography with gradient elution on a C₁₈ column and with fluorescence detection (excitation at 280 nm and emission above 389 nm). Mean recoveries ranged from 85.4 to 104%, and relative standard deviations ranged from 1.06 to 5.58% in samples spiked at concentrations of 10.0–863.8 ng/g. The method detection limit for sarafloxacin was 1.4 ng/g.