title: Determination of fatty acid ethyl esters in dried blood spots by LC-MS/MS as markers for ethanol intake: application in a drinking study.
abstract: The forensic utility of fatty acid ethyl esters (FAEEs) in dried blood spots (DBS) as short-term confirmatory markers for ethanol intake was examined. An LC-MS/MS method for the determination of FAEEs in DBS was developed and validated to investigate FAEE formation and elimination in a drinking study, whereby eight subjects ingested 0.66-0.84 g/kg alcohol to reach blood alcohol concentrations (BAC) of 0.8 g/kg. Blood was taken every 1.5-2 h, BAC was determined, and dried blood spots were prepared, with 50 μL of blood, for the determination of FAEEs. Lower limits of quantitation (LLOQ) were between 15 and 37 ng/mL for the four major FAEEs. Validation data are presented in detail. In the drinking study, ethyl palmitate and ethyl oleate proved to be the two most suitable markers for FAEE determination. Maximum FAEE concentrations were reached in samples taken 2 or 4 h after the start of drinking. The following mean peak concentrations (c̅(max)) were reached: ethyl myristate 14 ± 4 ng/mL, ethyl palmitate 144 ± 35 ng/mL, ethyl oleate 125 ± 55 ng/mL, ethyl stearate 71 ± 21 ng/mL, total FAEEs 344 ± 91 ng/mL. Detectability of FAEEs was found to be on the same time scale as BAC. In liquid blood samples containing ethanol, FAEE concentrations increase post-sampling. This study shows that the use of DBS fixation prevents additional FAEE formation in blood samples containing ethanol. Positive FAEE results obtained by DBS analysis can be used as evidence for the presence of ethanol in the original blood sample.
authors.affiliation: Institute of Forensic Medicine, University of Bern, Bühlstrasse 20, 3012, Bern, Switzerland. marc.luginbuehl@irm.unibe.ch.
authors.forename: Marc
authors.initials: M
authors.lastname: Luginbühl
authors.affiliation: Institute of Forensic Medicine, University of Bern, Bühlstrasse 20, 3012, Bern, Switzerland.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Schröck
authors.affiliation: Institute of Forensic Medicine, University of Bern, Bühlstrasse 20, 3012, Bern, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: König
authors.affiliation: Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012, Bern, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schürch
authors.affiliation: Institute of Forensic Medicine, University of Bern, Bühlstrasse 20, 3012, Bern, Switzerland.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Weinmann
mesh_terms: D000328:Adult; D000428:Alcohol Drinking; D015415:Biomarkers / Q000097:blood*; D002853:Chromatography, Liquid / Q000379:methods*; D004952:Esters / Q000737:chemistry; D000431:Ethanol / Q000008:administration & dosage* / Q000097:blood; D005227:Fatty Acids / Q000097:blood* / Q000737:chemistry; D005260:Female; D006801:Humans; D057230:Limit of Detection; D008297:Male; D053719:Tandem Mass Spectrometry / Q000379:methods*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D004952:Esters; D005227:Fatty Acids; D000431:Ethanol
keywords: Abstinence monitoring; Alcohol marker; Dried blood spots; Fatty acid ethyl ester; LC–MS/MS; Whole blood