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Collecting Hair Samples for Hair Cortisol Analysis in African Americans
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Is one hair lock really representative?

Franz Dussy1, Nicholas Carson, Sarah Hangartner

  • 1Forensische Chemie und Toxikologie, Institut fuer Rechtsmedizin, Basel, CH-4056, Switzerland.

Drug Testing and Analysis
|May 13, 2014
PubMed
Summary

Forensic hair analysis shows significant variability in analyte concentrations between locks from the same head. This impacts the reliability of reassessments and cut-off value interpretations in forensic toxicology.

Keywords:
MDMAcaffeineethyl glucuronidehair analysishair lockvariation

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Area of Science:

  • Forensic toxicology
  • Analytical chemistry
  • Human biochemistry

Background:

  • Hair analysis is crucial in forensic investigations for detecting substance use.
  • Standard practice involves analyzing a single hair lock, with a second retained for potential reassessment.
  • Reproducibility of analyte concentrations across different hair locks from the same individual is critical for reliable interpretation.

Observation:

  • Analyzed ethyl glucuronide and caffeine concentrations in 10 hair locks from three social drinkers.
  • Hair locks were collected from different scalp areas of the same individuals, covering the same time period.
  • Investigated the variability of analyte concentrations within individuals.

Findings:

  • Individual coefficients of variation ranged from 14% to 28% for ethyl glucuronide.
  • Coefficients of variation for caffeine ranged from 13% to 62%.
  • Concentration differences between hair locks varied by factors of 1.6 to 4.2 for the highest to lowest values.

Implications:

  • Findings highlight significant intra-individual variability in hair analyte concentrations.
  • This variability impacts the reliability of reassessing results using a second hair lock in forensic cases.
  • The observed variations are crucial for interpreting forensic results, especially when relying on specific cut-off values.