Determination of grepafloxacin and clinafloxacin by capillary zone electrophoresis

A simple and rapid capillary zone electrophoresis determination method with UV detection of grepafloxacin and clinafloxacin has been developed. The separation was performed in 35 mM borate–35 mM phosphate buffer solution (pH 8.6), containing 6% (v/v) of acetonitrile. Analyses were realised using fused-silica capillaries (57 cm length×75 μm I.D.) and the operating conditions were: 15 kV applied voltage, 30 °C and detection at 279 nm. Piromidic acid was used as an internal standard. The linear concentration range of application was 1.0–120.0 μg ml−1 for both compounds, with a detection limit of 0.2 μg ml−1 for grepafloxacin and 0.3 μg ml−1 for clinafloxacin. The analysis yielded good reproducibility (RSD between 3.37 and 1.74%). It was applied to the determination of grepafloxacin and clinafloxacin in human and rat urine samples. The method was validated using HPLC as a reference method. Recovery levels were between 94.5 and 103%.