High-performance liquid chromatographic determination of isofraxidin in rat plasma

For the first time a high-performance liquid chromatographic (HPLC) method, with liquid-liquid extraction and ultraviolet (UV) absorbance defection, has been developed for quantification of isofraxidin in rat plasma. The analysis was performed on a Diamonsil C-18 column (200mm x 4.6mm i.d., 5 mu m particle size) with acetonitrile-0.05% phosphoric acid, 26:74 (v/v), as isocratic mobile phase. The linear range was 0.05-8.0 mu g mL(-1) and the lower limit of quantification was 0.05 mu g mL(-1). The intra and inter-day relative standard deviation (RSD) for measurement of 0.25, 2.0, and 6.0 mu g mL(-1) quality-control (QC) samples ranged from 5.7 to 6.4% and from 6.3 to 7.9%, respectively. Accuracy, as relative error (RE), was from +/- 5.8% to +/- 7.3%. The method was validated for specificity, accuracy, and precision and was successfully used in a pharmacokinetic study of isofroxidin in rat plasma after administration of Ciwujia extract.