A rapid and simple gas-liquid chromatographic determination of valproic acid (alpha-propyl-valeric acid) in serum.

A simple and rapid gas-liquid chromatographic method for the determination of valproic acid in serum is described. Valproic acid is extracted from acidified serum into chloroform and analyzed by gas-liquid chromatography using an FFAP column. The sensitivity of the method is 5 mumol/l and the within-run and day-to-day precisions (CV) are 4.5% or better. Analytical recovery is estimated to exceed 98% and no interference from other drugs or constituents of serum has been observed. The method was used to study the half-life of valproic acid in five healthy persons receiving a single oral dose of the drug, and the technique is well adapted to the routine monitoring of epileptic patients. In routine analysis, the determination of 50 serum samples may be performed by one technician during a normal working day.