title: Determination of urinary valproylcarnitine by gas chromatography-mass spectrometry with selected-ion monitoring.
abstract: A modified method for the determination of valproylcarnitine in urine samples of patients receiving sodium valproate by gas chromatography-mass spectrometry with selected-ion monitoring is described. The chemically analogous internal standard 2-ethylpentanoylcarnitine was added to the urine samples. Valproic acid and its metabolites were removed by extraction with chloroform at pH 5.0. The samples were then applied onto a C18 Sep-Pak column. Inorganic and water soluble compounds were washed out with water. Valproylcarnitine and internal standard were eluted with methanol and were derivatized to the corresponding acyl-containing lactones by heating at 100 degrees C for 60 min in dimethylformamide. Urinary valproylcarnitine levels of epileptic patients receiving valproate were determined according to the present method. The data obtained might be useful for diagnosis of carnitine deficiency.
authors.affiliation: Department of Pharmacy, Tottori University School of Medicine, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Muro
authors.forename: T
authors.initials: T
authors.lastname: Tatsuhara
authors.forename: T
authors.initials: T
authors.lastname: Sugimoto
authors.forename: M
authors.initials: M
authors.lastname: Woo
authors.forename: N
authors.initials: N
authors.lastname: Nishida
authors.forename: K
authors.initials: K
authors.lastname: Murakami
authors.forename: Y
authors.initials: Y
authors.lastname: Yamaguchi
mesh_terms: D002138:Calibration; D002251:Carbon Tetrachloride; D002331:Carnitine / Q000031:analogs & derivatives* / Q000652:urine; D004126:Dimethylformamide; D004355:Drug Stability; D004827:Epilepsy / Q000188:drug therapy / Q000652:urine; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008832:Microchemistry; D012680:Sensitivity and Specificity; D014635:Valproic Acid / Q000627:therapeutic use / Q000652:urine
chemical_list: D014635:Valproic Acid; D004126:Dimethylformamide; C044923:valproylcarnitine; D002251:Carbon Tetrachloride; D002331:Carnitine