GC-MSMS determination of EtG on real hair samples and medicolegal evaluation of alcohol use and abuse

EtG is a minor non-oxidative ethanol metabolite, resulting from the enzymatic glucuronidation of ethanol in the liver. This small molecule can be detected in several body fluids and tissues for variable intervals of time after ethanol ingestion. Furthermore, there is a growing interest in its use in epidemiological studies in order to investigate drinking patterns and correlation to chronic disease and mortality. Currently, the consensus of the Society of Hair Testing (SoHT) describes that concentration of EtG in hair is expected to be above a cut-off value of 30pg/mg for chronic heavy drinkers, corresponding to a daily ethanol intake >60g. The evaluation of EtG on keratinic matrices to investigate the history of alcohol use and abuse in an individual is not usually carried out to assess the cause of death. It can, however, provide extremely valuable information for the investigation when the case is one of legal relevance. For EtG analysis, the specimen was decontaminated by washing with organic solvents, then dried and finely shredded in 1–2mm fragments; 50mg of sample was then put overnight in 2mL of water with an appropriate concentration of internal standard EtG-d5. The supernatant was purified with cationic bed Solid-Phase Extraction (SPE) and derivatized with MSTFA before analysis in Gas Chromatography-Electron Ionization-Triple Quadrupole (GC-EI-QQQ). In this study, female subjects whose toxicological analysis had been requested following autopsy to help determine cause of death were considered. On both subjects, a high value of alcohol had been found in conventional matrices such as central and peripheral blood, vitreous humor, urine, and gastric content. Therefore, it was interesting to analyze whether these values may be the result of a sporadic assumption of alcohol or coherent with an alcoholic behavior. For this reason, EtG analysis was carried out on hair samples, both on a full-length sample to determine an average concentration in the months before death and on multiple segments to evaluate the history of alcohol consumption over time.