Optimization and validation of a high performance liquid chromatography method for rapid determination of sinafloxacin, a novel fluoroquinolone in rat plasma using a fused-core C18-silica column

A novel, simple and rapid high performance liquid chromatographic method has been developed and validated for the determination of sinafloxacin, a new fluoroquinolone, in rat plasma using 96-well protein precipitation, fused-core C18-silica column (4.6 mm × 50 mm, 2.7 μm) packed with a new solid support, which is made of 2.7 μm particles that consist of a 1.7 μm solid core covered with a 0.5 μm thick shell of porous silica.The chromatographic separation was achieved with a mobile phase of 20:80 (v/v) of acetonitrile and phosphate buffer (pH = 3.0) at a flow rate of 1 ml min−1. Fluorescence detection was employed with λex 295 nm and λem 505 nm. Lomefloxacin was used as internal standard (IS). The total analysis time was as short as 3 min. The method was sensitive with a limit of detection (LOD) of 2 ng ml−1, with good linearity (R2 = 0.9996) over the linear range of 5–500 ng ml−1. The intra-day and inter-day precision was less than 5.8% and accuracy ranged from 100.3% to 103.5% for quality control (QC) samples at three concentrations of 10, 50 and 400 ng ml−1.The fused-core C18-silica column method offered high sample throughput, low injection volume and low consumption of organic solvents. The method was successfully employed in the pharmacokinetic study of sinafloxacin formulation product after tail vein injection to healthy rats.