High performance liquid chromatography–electrospray ionization mass spectrometric determination of balofloxacin in human plasma and its pharmacokinetics

A selective and sensitive high performance liquid chromatography–electrospray ionisation–mass spectrometry method has been developed for the determination of balofloxacin (BLFX) in human plasma. The sample preparation was a liquid–liquid extraction, and chromatographic separation was achieved with an Agilent ZORBAX 300SB C18 2.1 mm × 150 mm column using a mobile phase comprised of methanol–water (10 mM CH3COONH4, pH 3.0) = 40:60 (v/v). Standard curves were linear (r = 0.9992) over the concentration range of 0.03–3 μg/ml and had good accuracy and precision. The within- and between-batch precisions were within 10% relative standard deviation (R.S.D.). The limit of detection (LOD) was 0.02 μg/ml. The validated HPLC–electrospray ionization (ESI)–MS method has been used successfully to study balofloxacin pharmacokinetics in healthy volunteers.