Abstract: A method was established for the analysis of gatifloxacin or fleroxacin in water sample by ultrasonic assisted hydrophobic ionic liquid (1-hexyl-3-methylimidazolium hexafluorophosphate, [C6mim][PF6]) liquid-phase microextraction coupled with high performance liquid chromatography(HPLC). The pH value of solution, amount of ionic liquid and other factors which might affect the extraction efficiency were researched. To gatifloxacin water sample at pH=3.3 and fleroxacin water sample at pH=2.1 was added 0.4 mL of [C6mim][PF6], respectively, for ultrasonic extraction. After extraction, phase separation was performed by centrifugation. The sediment phase were injected into the HPLC system for analysis. By this method, the linear ranges for analysis are 0.5~100 μg/L and the relative standard deviations(n=5) for them are 2.80 and 5.93, respectively. The limits of detection(3S/N) for gatifloxacin and fleroxacin are 0.46 and 0.97 μg/L, respectively. Under the above mentioned conditions, the extraction recoveries for gatifloxacin or fleroxacin water samples were found to be 80.5%~89.5% and 93.3%~99.0%, respectively.

Key words: gatifloxacin, fleroxacin, ionic liquid, ultrasounic extraction