Related Experiment Video
Updated: Sep 23, 2026

High-throughput and Comprehensive Drug Surveillance Using Multisegment Injection-Capillary Electrophoresis-Mass Spectrometry
Published on: April 23, 2019
Direct observation of 3-keto-valproate in urine by 2D-NMR spectroscopy
Shunsuke Meshitsuka1, Tatsuya Koeda, Hideki Muro
1Department of Biomedical Science, Institute of Regenerative Medicine and Biofunction, Tottori University Graduate School of Medical Science, Tottori 683-8503, Yonago, Japan. mesh@grape.med.tuttori-u.ac.jp
Background:
It is known that valproate and its metabolites cause hepatotoxicity. The drug monitoring of valproate is important to determine an effective dose to keep an appropriate concentration in blood.
Methods:
In a 2-dimensional (2D)-NMR spectrum of double quantum filtered correlation spectroscopy (DQF-COSY), clear correlation peaks were ascertained to be due to 3-keto-valproate, which was a beta-oxidation product of valproate.
Results:
A predominant metabolite of valproate was observed by proton NMR spectroscopy in the crude urine of a particular patient with metabolic disorder. The assignment of the signals was determined by synthesized 3-keto-valproic acid ethyl ester. The concentration of 3-keto-valproate in the urine was calculated to be 631 microg/mg creatinine by the integration of the peak of the isolated triplet methyl protons of C(5) at 1.016 ppm.
Conclusion:
Although the NMR spectra of crude urine of the patients who took valproate were usually complicated with many metabolites, the signals of 3-keto-valproate in a DQF-COSY spectrum of the urine of patients were easily connected according to the present assignment. The NMR analysis of the urine of patients who are prescribed valproate is useful for therapeutic drug monitoring and for checking the compliance of the patients.
Related Concept Videos
¹H NMR of Labile Protons: Deuterium (²H) Substitution
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
NMR Spectroscopy and Mass Spectrometry of Aldehydes and Ketones
Spectroscopy of Carboxylic Acid Derivatives
In the...
¹H NMR of Labile Protons: Temporal Resolution
The –OH proton in alcohols typically appears in the range of δ 2 to 5 ppm but can vary depending on the specific...
Proton (¹H) NMR: Chemical Shift
Absorption signals of all the protium nuclei in a...

