title: Determination of ethyl glucuronide and ethyl sulfate from dried blood spots.
abstract: BACKGROUND
  Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are non-oxidative minor metabolites of ethanol. They are detectable in various body fluids shortly after initial consumption of ethanol and have a longer detection time frame than the parent compound. They are regarded highly sensitive and specific markers of recent alcohol uptake. This study evaluates the determination of EtG and EtS from dried blood spots (DBS), a simple and cost-effective sampling method that would shorten the time gap between offense and blood sampling and lead to a better reflectance of the actual impairment.
  
  
  METHODS
  For method validation, EtG and EtS standard and quality control samples were prepared in fresh human heparinized blood and spotted on DBS cards, then extracted and measured by an LC-ESI-MS/MS method. Additionally, 76 heparinized blood samples from traffic offense cases were analyzed for EtG and EtS as whole blood and as DBS specimens. The results from these measurements were then compared by calculating the respective mean values, by a matched-paired t test, by a Wilcoxon test, and by Bland-Altman and Mountain plots.
  
  
  CONCLUSIONS
  Calibrations for EtG and EtS in DBS were linear over the studied calibration range. The precision and accuracy of the method met the requirements of the validation guidelines that were employed in the study. The stability of the biomarkers stored as DBS was demonstrated under different storage conditions. The t test showed no significant difference between whole blood and DBS in the determination of EtG and EtS. In addition, the Bland-Altman analysis and Mountain plot confirmed that the concentration differences that were measured in DBS specimens were not relevant.
authors.affiliation: Institute of Forensic Medicine, University of Bern, Bern, Switzerland.
authors.forename: Ana
authors.initials: A
authors.lastname: Hernández Redondo
authors.forename: Alexandra
authors.initials: A
authors.lastname: Schroeck
authors.forename: Beat
authors.initials: B
authors.lastname: Kneubuehl
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Weinmann
mesh_terms: D000428:Alcohol Drinking / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D001774:Blood Chemical Analysis; D001801:Blood Stains; D002853:Chromatography, Liquid; D053593:Forensic Toxicology / Q000379:methods; D005965:Glucuronates / Q000097:blood*; D006801:Humans; D013058:Mass Spectrometry; D013048:Specimen Handling; D013463:Sulfuric Acid Esters / Q000097:blood*
chemical_list: D015415:Biomarkers; D005965:Glucuronates; D013463:Sulfuric Acid Esters; C093924:ethyl glucuronide; C011612:diethyl sulfate