A fully validated high-performance liquid chromatography-tandem mass spectrometry method for the determination of ethyl glucuronide in hair for the proof of strict alcohol abstinence.

Hair analysis has become a powerful tool for the detection of chronic and past drug consumption. For several years, it has been possible to determine even the intake of ethanol in hair samples by detecting the ethanol metabolites ethyl glucuronide or fatty acid ethyl esters. Recently, new requirements were published for the use of EtG as an abstinence test (c(EtG) < 7 pg/mg) as well as for heavy-drinking detection (c(EtG) > 30 pg/mg). In order to perform abstinence tests, a sensitive LC-MS/MS procedure has been developed and fully validated according to the guidelines of forensic toxicology. The nine-point calibration curve showed linearity over the range of concentrations from 2-1,000 pg/mg. Detection and quantification limits were 1 and 4 pg/mg respectively. The intra- and inter-day precision and accuracy were always better than 20%. The validated procedure has successfully been applied to perform abstinence tests and to analyze hair samples from persons in withdrawal treatment. Concentrations between <LOQ and 400 pg/mg were determined. In some cases, interfering peaks complicated the quantification to some extent. First results using varied chromatographic conditions showed constituting results. However, modified chromatographic conditions help substantiate critical results, especially if the determined EtG concentration is close to a cut-off value.