Determination of Valproic Acid by Flame-Ionization Gas-Liquid Chromatography

Abstract

A rapid method is described for determination of valproic acid in biologic fluids by utilization of a gas chromatograph equipped with a flame-ionization detector. After caproic acid is added to the biologic specimen as an internal standard, the specimen is extracted with 10% ethyl acetate in hexane, followed by direct chromatographic analysis using an SP-1000 liquid-phase column. The procedure does not require solvent evaporation. Recovery of the drug is approximately 100%. Inter-assay coefficient of variation is less than 4%.