N-Acetyltaurine as a novel urinary ethanol marker in a drinking study
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The forensic utility of N-acetyltaurine (NAcT) in urine as a marker for ethanol intake was examined. A HILIC-based liquid chromatography method for the mass spectrometric determination of NAcT, taurine, and creatinine in urine was developed and validated to investigate NAcT formation and elimination in a drinking study. Thereby, eight subjects ingested 0.66 to 0.84 g/kg alcohol to reach a blood alcohol concentration (BAC) of 0.8 g/kg. Blood and urine were taken every 1.5–2 h, during the first 8 h. NAcT and taurine levels were measured and corrected for the urine’s dilution by normalization to a creatinine concentration of 1 mg/mL. For the determination of NAcT and taurine, uncorrected lower limits of quantitation (LLOQs) were at 0.05 μg/mL of urine. In the drinking study, NAcT proved to be an endogenous compound, which is present at a range of 1.0 to 2.3 μg/mL in urine of alcohol-abstinent subjects. Maximum NAcT concentrations were reached in samples taken 3 to 6 h after the start of drinking, whereby an upregulation in N-acetyltaurine could be found for all the subjects. The mean peak concentrations (c̅ max) of 14 ± 2.6 μg/mL (range 9–17.5 μg/mL) were reached. Within 24 h, the NAcT levels declined to endogenous concentrations. The detectability of NAcT was found to be slightly shifted compared to BAC: When BAC was not detectable anymore, NAcT levels were still elevated. After 24 h, when ethyl glucuronide (EtG) and ethyl sulfate (EtS) were still detectable, NAcT concentrations showed endogenous levels again. Positive NAcT results can be used as an indicator for recent alcohol consumption. A direct relationship between NAcT and taurine concentrations could not be found.
KeywordsN-Acetyltaurine Taurine Alcohol marker Abstinence monitoring Urine analysis LC-MS/MS
We would like to thank Sidonia Guggisberg, Anita Iannone, Anja Kaiser, Severine Krönert, Nadja Utiger, and Thomas Wüthrich of the Forensic Toxicology and Chemistry Laboratory of the Institute of Forensic Medicine Bern for the determination of blood alcohol concentrations.
Compliance with ethical standards
The drinking study has been approved by the Cantonal Ethics Commission Bern (064/13) on March 3, 2014. The participants of the drinking study gave informed consent for the analysis of direct alcohol marker in the collected samples.
Conflict of interest
The authors declare that they have no conflict of interest.
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