A method for determining valproic acid in human whole blood and urine via gas chromatography-mass spectrometry and small-scale inter-laboratory trial

Akira Namera; Kyoko Uekusa; Takeshi Saito; Kanji Yoshimoto; Naoki Ishiuchi; Kazuhiro Murata; Masataka Nagao

doi:10.1016/j.legalmed.2022.102133

A method for determining valproic acid in human whole blood and urine via gas chromatography-mass spectrometry and small-scale inter-laboratory trial

Leg Med (Tokyo). 2022 Nov:59:102133. doi: 10.1016/j.legalmed.2022.102133. Epub 2022 Aug 17.

Authors

Akira Namera¹, Kyoko Uekusa², Takeshi Saito³, Kanji Yoshimoto⁴, Naoki Ishiuchi⁵, Kazuhiro Murata⁶, Masataka Nagao⁶

Affiliations

¹ Department of Forensic Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan. Electronic address: namera@hiroshima-u.ac.jp.
² Department of Legal Medicine, Nippon Medical School, Japan.
³ Department of Emergency and Critical Care Medicine, Tokai University School of Medicine, Japan.
⁴ Department of Food Sciences and Biotechnology, Graduate School of Science and Technology, Hiroshima Institute of Technology, Japan.
⁵ Center for Cause of Death Investigation Research, Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan.
⁶ Department of Forensic Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan.

PMID: 35998544
DOI: 10.1016/j.legalmed.2022.102133

Abstract

A simple and cost-effective method for analyzing valproic acid (VPA) in biological samples was developed. VPA was extracted in methyl tertiary-butyl ether (MTBE) and derivatized using trimethylsilyldiazomethane. The MTBE extract was analyzed by gas chromatography-mass spectrometry (GC-MS). The extraction recovery in human whole blood and urine was over 90 %, with good linearity in the range of 1.0 to 250 µg/mL of VPA. The RSD for 2.0, 20, and 200 μg/mL VPA in whole blood ranged from 0.9 to 4.7 % for intra-day and 1.5 to 5.9 % for inter-day. The RSD for 2.0, 20, and 200 μg/mL VPA in urine ranged from 1.9 to 2.6 % for intra-day and 1.2 to 2.9 % for inter-day. As a preliminary cross-validation study, a cross-check was conducted using blinded concentration samples. The results demonstrated that the assay data of the two laboratories were comparable.

Keywords: GC-MS; Trimethylsilyldiazomethane; Urine; Valproic acid; Whole blood.

MeSH terms

Gas Chromatography-Mass Spectrometry / methods
Humans
Methyl Ethers*
Valproic Acid*

Substances

Valproic Acid
methyl tert-butyl ether
Methyl Ethers