Quantification of ethyl glucuronide in hair: evaluation of a commercially available LC-MS/MS kit

Abstract Objectives In this study, the first commercially available CE-certified test kit for the determination of ethyl glucuronide (EtG) in hair (EUREKA – Lab Division, Chiaravalle, Italy) known to us was evaluated. The aim was to assess the analytical performance of the assay with regard to clinical and forensic applications. The results provide a basis for evaluating the kit’s suitability for routine laboratory use and for the objective assessment of long-term alcohol consumption in sensitive clinical and legal decision-making processes. Methods 50 mg of ground hair is used for analysis. An isotopically labeled internal standard is added for later quantification. After extraction, 10 µl aliquot of the resulting solution is injected into the LC-MS/MS system. The injection interval is 7.5 min. For the measurement an QTRAP 6500+ tandem mass spectrometer (AB Sciex, Darmstadt, Germany) and an Agilent UHPLC system (Waldbronn, Germany) were used. The method was validated according to the guidelines of the GTFCh directive. Results The limit of detection of the commercial EtG test kit was 1.6 pg/mg hair. Intra-assay and inter-assay coefficients of variation were determined to be <9.2 %. Participation in interlaboratory proficiency tests was successful in all cases. A correlation of r=0.98 was observed between the commercial test kit and an established LC-MS/MS method. Conclusions The commercial test kit is suitable for quantifying EtG in hair in order to estimate alcohol consumption or provide evidence of abstinence, in accordance with CTU criteria for participants undergoing driving aptitude assessments.