A novel method for the determination of trace gatifloxacin was established by resonance fluorescence techniques. It was based on the fact that oxidation of rhodamin 6G by hydrogen peroxide and Cu 2þ was inhibited by gatifloxacin in Tris-HCl buffer medium and in presence of cetyl trimethyl ammonium bromide. The enhanced intensity (DF) of resonance fluorescence at 540 nm was proportional to the concentration of gatifloxacin in the range of 9.8 Â 10 À3 À 1.75 lg mL À1 . The limit of detection was 2.9 ng mL À1 and the average recovery was 101.8% (n ¼ 6) for gatifloxacin. The present method was applied to the determination of trace gatifloxacin in milk and biological fluids, and the obtained results were in good agreement with those obtained by HPLC.

No abstract