Determination of lomefloxacin in plasma samples by HPLC with fluorescence detection. Application to pharmacokinetic studies

A sensitive HPLC method with fluorescence detection is described for the analysis of lomefloxacin (LOM) in biological samples; sarafloxacin (SAR) is used as internal standard. Sample preparation was performed by adding phosphate buffer (pH 7.4, 0.1m) then extraction with trichloromethane. LOM and the internal standard were separated by HPLC on a reversed-phase column with aqueous phosphate solution-acetonitrile, 80∶20, as mobile phase. The concentrations of SAR and LOM eluting from the column (retention times 2.35 and 3.67 min, respectively) were monitored by fluorescence detection detection at λex 338 and λem 425 nm. The detection and quantitation limits were 8 and 15 ng mL−1, respectively. Standard curves were linearly related to concentration in the range 8–2000 ng mL−1. Recovery was found to be 104.8% for LOM. The method was applied to the determination of LOM in plasma samples collected during pharmacokinetic studies.