Simultaneous determination of cefepime and the quinolones garenoxacin, moxifloxacin and levofloxacin in human urine by HPLC-UV

A liquid chromatographic method with a C-18 column and acetonitrile/0.1M phosphoric acid/sodium hydroxide buffer (pH 3.0)/0.01M n-octyl-amine (pH 3.0) as mobile phase in gradient mode has been developed and optimised for the simultaneous determination of the cephalosporin cefepime and the quinolones garenoxacin, levofloxacin and moxifloxacin. Identification and quantification was carried out with a diode-array UV detector, with working wavelengths of 256 nm for cefepime, 292 nm for levofloxacin, 294 nm for moxifloxacin and 282 nm for garenoxacin. The mobile flow-rate and sample volume injected were 1mL min(-1) and 20 mu L, respectively. The retention times and detection limits for each antibiotic were 4.9 min and 1.9 mu g mL(-1) for cefepime, 7.5 min and 2.2 mu g mL(-1) for levofloxacin, 8.9 min and 2.7 mu g mL(-1) for moxifloxacin and 10.7 min and 1.8 mu g mL(-1) for garenoxacin, respectively. The method was applied to the determination of the four molecules in spiked samples of human urine.