Separation of levofloxacin, ciprofloxacin, gatifloxacin, moxifloxacin, trovafloxacin and cinoxacin by high-performance liquid chromatography: application to levofloxacin determination in human plasma.

A selective, sensitive and accurate liquid chromatographic method with UV and fluorescence detection was developed, validated and applied for the determination of fluoroquinolones in human plasma. The effects of mobile phase composition, ion-pair and competing-base reagents, buffers, pH, and acetonitrile concentrations were investigated on the separation of six quinolones (cinoxacin, levofloxacin, ciprofloxacin, gatifloxacin, moxifloxacin and trovafloxacin). Sample preparation was carried out by adding internal standard and displacing agent and processing by ultrafiltration. This method uses ultraviolet and fluorescence detection and separation using a C(18) column. The recovery, selectivity, linearity, precision, and accuracy of the method were evaluated from spiked human plasma samples. The method was successfully applied to patient plasma samples in support of a levofloxacin pharmacokinetic study.