Abstract
A simple and rapid method for routine measurement of valproic acid in serum has been established by high performance liquid chromatography. To 0.2ml of serum sample is added 0.2ml of acetonitrile solution containing thymol as an internal standard (2μg ml-1). After centrifugation, a 20μl aliquot of the supernatant is injected directly into a liquid chromatograph. The chromatographic procedure utilizes a reversed phase ODS column with a mobile phase consisting of 0.05M phosphate buffer(pH 3.0)-acetonitrile-isopropanol (60:25:15) at a flow rate of 0.7ml min-1. Valproic acid was detected by UV absorption at 220nm. The calibration curve was linear from 20 to 120μg ml-1 valproic acid in serum. This method has been applied successfully to monitoring routine serum levels of valproic acid. The results agreed fairly well with those obtained by gas chromatography.
