AN IMPROVED GC METHOD FOR RAPID ANALYSIS OF VALPROIC ACID IN HUMAN PLASMA WITHOUT DERIVATIZATION

A simple, reproducible and rapid gas chromatographic method for precise determination of valproic acid (VPA) in human plasma has been developed. Total time for sample preparation and GC analysis is less than 45 min. After plasma protein precipitation, VPA was extracted into chloroform with suitable recovery. By using Stabilwax®-DA capillary GC column, a symmetrical gas chromatographic peak was obtained without the need for derivatization. The calibration curve was proved to be linear (r2 = 0.998) in a wide concentration range (0.45-100 μg/ml). Inter-day and intra-day accuracy and precision of this method was investigated during the method validation and the method has good precision and accuracy. This method is highly reproducible with a limit of detection 150 ng/ml of VPA in human plasma and could be used in TDM and pharmacokinetic studies.