Environment

Journal of Chromatography B, 877 (2009) 2337–2343

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Journal of Chromatography B

journal homepage: www.elsevier.com/locate/chromb

Development and validation of a gas chromatography–negative chemical ionization tandem mass spectrometry method for the determination of ethyl glucuronide in hair and its application to forensic toxicology

Hicham Kharbouche, Frank Sporkert ∗ , Stéphanie Troxler, Marc Augsburger, Patrice Mangin, Christian Staub

University Center of Legal Medicine, West Switzerland, rue du Bugnon 21, CH-1011 Lausanne, Switzerland

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Ethyl glucuronide (EtG) is a minor and direct metabolite of ethanol. EtG is incorporated into the growing hair allowing retrospective investigation of chronic alcohol abuse. In this study, we report the development and the validation of a method using gas chromatography–negative chemical ionization tandem mass spectrometry (GC–NCI-MS/MS) for the quantification of EtG in hair. EtG was extracted from about 30 mg of hair by aqueous incubation and purified by solid-phase extraction (SPE) using mixed mode extraction cartridges followed by derivation with perfluoropentanoic anhydride (PFPA). The analysis was performed in the selected reaction monitoring (SRM) mode using the transitions m/z 347 → 163 (for the quantification) and m/z 347 → 119 (for the identification) for EtG, and m/z 352 → 163 for EtG-d5 used as internal standard. For validation, we prepared quality controls (QC) using hair samples taken post mortem from 2 subjects with a known history of alcoholism. These samples were confirmed by a proficiency test with 7 participating laboratories. The assay linearity of EtG was confirmed over the range from 8.4 to 259.4 pg/mg hair, with a coefficient of determination (r2 ) above 0.999. The limit of detection (LOD) was estimated with 3.0 pg/mg. The lower limit of quantification (LLOQ) of the method was fixed at 8.4 pg/mg. Repeatability and...