Determination of Valproic Acid by Hplc in Human Blood and Its Relationship to Therapeutic Drug Monitoring

A novel HPLC method for the determination of valproic acid (VPA) in human serum using nonanoic acid as internal standard (I.S.) is described in this article. The eluates were separated with a reverse phase column of the dimensions C18 250 × 4.6 mm internal diameter maintained at a temperature of 48 °C. A mobile phase consisting of acetonitrile and 29mM phosphate buffer (pH 3.5) 49: 51 v/v was used at a flow rate of 1.2 ml/min. Wavelength used was 220 nm during valproic acid retention. The method was linear over a concentration range of 10 to 100 μg/ml for valproic acid. Recovery was greater than 93% over a concentration range of 20 to 100 μg/ml respectively. The retention time for valproic acid and Nonanoic acid was 9.7 and 13.8 minutes. The method is simple, rapid, accurate and sensitive and can be used for Therapeutic Drug Monitoring (TDM) in epileptic patient population.