Simplified HPLC method with spectrophotometric detection for the assay of clofibric acid in rat plasma

A simple and rapid reversed-phase HPLC method for the assay of clofibric acid in rat plasma is presented. After a simultaneous deproteinization-extraction step of a 200 mu L plasma sample with a solution of propyl paraben in acetonitrile, the clear extract was injected onto a Microsorb-MV C18 chromatographic column and eluted with 1% acetic acid in acetonitrile-water (45:55) at the rate of 0.8 mL/min. At the detection wavelength of 230 nm, clofibric acid and propyl paraben, the internal standard, eluted at 7.0 min and 5.5 min, respectively. Peak responses were linearly related to concentrations of clofibric acid in the range 1.5-30 mu g/mL, with a minimum detectable concentration of analyte of 75 ng on-column. Recoveries of clofibric acid from plasma samples spiked at 1.5-30 mu g/mL levels of analyte were >94% (range 94.6-99%). The proposed method was easily applied to the determination of the plasma plasma levels of clofibric acid derived from the oral and intraperitoneal administrations of clofibrate as a liquisolid compact and as the contents of a commercial soft gelatin capsule to rats.