Determination of CQP propionic acid in rat plasma and study of pharmacokinetics of CQP propionic acid in rats by liquid chromatography

A sensitive method for the determination of CQP propionic acid in rat plasma was developed and validated after solid-phase extraction. Chromatographic separation was achieved on a reversed-phase Alltima C18 column with the mobile phase of methanol–0.15% (v/v) phosphoric acid solution (pH 2.5) and step gradient elution resulted in a total run time of about 20 min. The analytes were detected by using UV detector at 345 nm. A good linear relationship was obtained in the concentration range of 50–12,800 ng/mL (r = 0.9998). The intra-day RSDs and the inter-day RSDs at the concentration of 200, 800, 6400 and 12,800 ng/mL were less than 7.0% and 11.0%, respectively. The intra-day accuracy ranged from 96.3 to 106.5% and the inter-day accuracy ranged from 98.6 to 113.4%, respectively. Average extraction recoveries ranged from 83.6 to 94.3% in plasma at the concentrations of 200, 800, 6400 and 12,800 ng/mL. This method was successfully applied to the pharmacokinetic studies on rats.