Ethyl glucuronide and ethyl sulphate determination in serum by liquid chromatography–electrospray tandem mass spectrometry

BackgroundEthyl glucuronide (EtG) and ethyl sulphate (EtS) are two ethanol metabolites that can be detected in serum up to 8 h after ethanol elimination. Their presence is therefore indicative of recent ethanol consumption in case of delayed sampling after an event (e.g. car crash).MethodsA LC–ESI–MS–MS method for the determination of EtG and EtS in serum was developed and validated. Two product ions together with the parent ions were monitored for identification. Pentadeuterated–EtG was used as internal standard.ResultsExcellent linearity for EtG (from 0.22 to 45 μmol/l) and EtS (from 0.40 to 80 μmol/l) was observed (r2 ≥ 0.9998). LOD and LLOQ were 0.04 and 0.20 μmol/l for EtG and 0.08 and 0.40 μmol/l for EtS, respectively. Accuracy (bias) and precision (relative standard deviation), studied at four different quality control levels, were always better than 7%. Matrix effects were found to be negligible. The method was applied to several samples obtained from known alcoholics and social drinkers.ConclusionsA sensitive and specific determination of EtG and EtS in serum samples was achieved despite a simple and fast sample preparation. To our knowledge, this is the first fully validated method for the simultaneous determination of the two alcohol metabolites in serum.