Investigations on the influence of different grinding procedures on measured ethyl glucuronide concentrations in hair determined with an optimized and validated LC-MS/MS method.

Ethyl glucuronide (EtG) analysis in hair is a suitable method for the retrospective determination of previous alcohol consumption. According to the German guidelines, EtG abstinence is improbable at c(EtG) > 7 pg/mg in the proximal 3 cm of scalp hair. The chromatography of the routinely used liquid chromatography-tandem mass spectrometry procedure was optimized by replacing the stationary phase. To simplify sample preparation, two different mills were tested, and an optimized grinding process was developed. The new method was successfully validated according to the guidelines of the German Society of Toxicological and Forensic Chemistry. Despite a simple extraction procedure without any cleaning steps, a very high sensitivity (limit of detection, 1.7 pg/mg; limit of quantitation, 2.3 pg/mg) could be achieved. Competitive analysis showed significantly higher EtG concentrations in pulverized versus cut hair samples. The strong impact of sample preparation on the determined EtG concentrations suggests the introduction of a standardized sample preparation method to produce comparable results.