title: Determination of ethyl glucuronide in human hair samples: A multivariate analysis of the impact of extraction conditions on quantitative results.
abstract: BACKGROUND
  Ethyl glucuronide (EtG), a minor metabolite of ethanol, is used as a direct alcohol biomarker for the prolonged detection of ethanol consumption. Hair testing for EtG offers retrospective, long-term detection of ethanol exposition for several months and has gained practical importance in forensic and clinical toxicology. Since quantitative results of EtG hair testings are included in interpretations, a rugged quantitation of EtG in hair matrix is important. As generally known, sample preparation is critical in hair testing, and the scope of this study was on extraction of EtG from hair matrix.
  
  
  METHODS
  The influence of extraction solvent, ultrasonication, incubation temperature, incubation time, solvent amount and hair particle size on quantitative results was investigated by a multifactorial experimental design using a validated analytical method and twelve different batches of authentic human hair material. Eight series of extraction experiments in a Plackett-Burman setup were carried out on each hair material with the studied factors at high or low levels. The effect of pulverization was further studied by two additional experimental series. Five independent samplings were performed for each run, resulting in a total number of 600 determinations.
  
  
  RESULTS
  Considerable differences in quantitative EtG results were observed, concentrations above and below interpretative cut-offs were obtained from the same hair materials using different extraction conditions. Statistical analysis revealed extraction solvent and temperature as the most important experimental factors with significant influence on quantitative results. The impact of pulverization depended on other experimental factors and the different hair matrices themselves proved to be important predictors of extraction efficiency.
  
  
  CONCLUSIONS
  A standardization of extraction procedures should be discussed, since it will probably reduce interlaboratory variabilities and improve the quality and acceptance of hair EtG analysis.
authors.affiliation: University Medical Center Hamburg-Eppendorf, Department of Legal Medicine, Toxicology, Hamburg, Germany. Electronic address: al.mueller@uke.de.
authors.forename: Alexander
authors.initials: A
authors.lastname: Mueller
authors.affiliation: University Medical Center Hamburg-Eppendorf, Department of Legal Medicine, Toxicology, Hamburg, Germany.
authors.forename: Hilke
authors.initials: H
authors.lastname: Jungen
authors.affiliation: University Medical Center Hamburg-Eppendorf, Department of Legal Medicine, Toxicology, Hamburg, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Iwersen-Bergmann
authors.affiliation: University Medical Center Hamburg-Eppendorf, Department of Legal Medicine, Toxicology, Hamburg, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Raduenz
authors.affiliation: University Medical Center Hamburg-Eppendorf, Department of Medical Biometry and Epidemiology, Hamburg, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Lezius
authors.affiliation: University Medical Center Hamburg-Eppendorf, Department of Legal Medicine, Toxicology, Hamburg, Germany.
authors.forename: Hilke
authors.initials: H
authors.lastname: Andresen-Streichert
mesh_terms: D000437:Alcoholism / Q000175:diagnosis; D015415:Biomarkers / Q000032:analysis; D002853:Chromatography, Liquid; D005965:Glucuronates / Q000032:analysis*; D006197:Hair / Q000737:chemistry*; D006801:Humans; D015999:Multivariate Analysis; D012997:Solvents; D013048:Specimen Handling / Q000379:methods*; D015813:Substance Abuse Detection / Q000379:methods; D053719:Tandem Mass Spectrometry; D013696:Temperature; D013997:Time Factors; D000069453:Ultrasonic Waves
chemical_list: D015415:Biomarkers; D005965:Glucuronates; D012997:Solvents; C093924:ethyl glucuronide
keywords: Alcohol biomarkers; Ethyl glucuronide; Hair testing; Mass spectrometry