Evaluation of a commercial LC-MS/MS assay for the quantification of ethyl glucuronide in urine for alcohol intake monitoring

Abstract

Background: A commercially available in vitro diagnostics (IVD)-approved mass spectrometric assay for the quantification of ethyl glucuronide (EtG) and ethyl sulfate (EtS) in urine (RECIPE Chemicals+Instruments GmbH, Munich, Germany) was verified for monitoring of recent alcohol intake after transplantation. Methods: For sample preparation, 50 μL of urine sample was mixed with an isotope-labeled internal standard solution. After centrifugation, 5 μL of the supernatant was analyzed by LC-MS/MS in a total run time of 3 min. An API 6500 tandem mass spectrometer (AB SCIEX, Toronto, Canada) combined with a Shimadzu UFLC system (Duisburg, Germany) was applied. Results: The limits of quantification for the commercial assay were 0.07 mg/L for EtG and 0.03 mg/L for EtS in urine. The coefficient of variation for both analytes was