MonitoringSerum VaiproicAcid by Gas Chromatographywith Electron-

I have developed a procedure to monitor, by gas chro-matography with electron-capture detection, the con-centration of vaiproic acid in serum. The valprolc acid Is derivatized into Its phenacyl ester. The assay Is very sensitive, measuring as little as 100 pg of valproic acid easily and accurately. Solvent extraction and concentration of the drug are not necessary; Instead, one only has to precipitate the serum proteins. n-Octanolc acid is used as the internal standard. The peak-height ratio of phenacyl valproate to phenacyl octanoate Is linearly related to concentration up to 200 mg of vaiproic acid per liter. Additional l(eyphrases: anticonvulsant drugs. pediatric chemistry Valproic acid is a newer member of the antiepileptic drugs in the North American market. Although a therapeutic rang