Determination of ethyl glucuronide levels in hair for the assessment of alcohol abstinence

Abstract

This study examined the potential of a highly sensitive LC-MS/MS method for the determination of EtG in head hair (i) to ascertain alcohol abstinence, (ii) to estimate the basal level of EtG (sub-ppb concentrations) in head hair in a population of alcohol abstainers and (iii) to suggest a revision of cut-off values for assessing alcohol abstinence. An UHPLC-MS/MS protocol previously developed was modified and validated again to detect low EtG levels in head hair samples from a population of 44 certain abstainers and teetotalers. Basal level of EtG in hair was determined by a standard addition quantification method. The validated UHPLC-MS/MS method allowed detecting and quantifying 0.5 and 1.0 pg/mg of EtG in hair, respectively. EtG concentrations lower than 1.0 pg/mg were determined for 95% of abstainers; 30% of them had non-detectable (<0.5 pg/mg) EtG values.Two samples evidenced EtG concentrations higher than 1.0 pg/mg that were subsequently explained by unintentional ethanol exposure. The method's feature of high analytical sensitivity makes it particularly suitable for alcohol abstinence ascertainment and, in the same time, allows to tentatively estimate basal EtG concentrations in hair around 0.8 ± 0.4 pg/mg. This finding opens a discussion on the possible origin of basal EtG concentration and potential sources of bias in the evaluation of alcohol abstinence. Cut-off value in the range of 1.0-2.0 pg/mg can be reliably proposed to support alcohol abstinence.

Sample preparation method for the combined extraction of ethyl glucuronide and drugs of abuse in hair

“…Hair analysis is usually done using ca. 10–50 mg of hair . The hair is cut and/or ground and subjected to extraction procedures after which the extract is enriched and clean‐up steps are performed.…”

Alcohol Biomarkers in Hair

“…Hypothetical basal levels of EtG around 0.8 6 0.4 pg/mg in hair from 26 children (teetotalers) and 16 adult abstainers were estimated using the method of standard addition and extrapolation and are believed to originate from ethanol-containing food, prescribed medicals, and cosmetic and hair care products [51]. In accordance, negative results with LOD of 1 pg/mg were also found for hair samples from 10 children [53].…”

Experiences in Child Hair Analysis

“…Pirro et al [35] have tentatively estimated basal ethyl glucuronide, the phase II metabolite of ethanol concentrations in hair around 0.8 6 0.4 pg/mg. Often, hair from children is used as blank hair during validation of methods or routine QC samples.…”