Abstract
A simple and rapid determination of 3-keto-valproate (3-keto-VPA) in urine is described by a metal capillary gas chromatography (GC) with a flame ionization detector (FID). 3-Keto-VPA was converted to 3-heptanone under acidic condition. 3-Keto-VPA-glucuronide was hydrolyzed to 3-keto-VPA by means of β-D-glucuronidase. 3-Heptanone thus formed was extracted with hexane and determined by GC. Suitable conditions for decarboxylation of 3-keto-VPA and hydrolysis of 3-keto-VPA ethyl ester (3-keto-VPA-Et) were also investigated. The present procedure does not require any derivatization or complicated separation techniques. Classifiable determinations of free 3-heptanone, free 3-keto-VPA and 3-keto-VPA-glucuronide were possible. A deactivated metal capillary column was applied for the determination of urinary 3-keto-VPA; its minimum detectable amount was about 0.1μg/ml in urine. The column was suitably inert, mechanically tough, and easier to handle than a fused silica one; the peaks on the chromatogram were almost symmetrical without any tailing or leading.
