LC-MS/MS Determination of Hair GHB: Is Segmental Analysis Useful for Exogenous Discrimination?

Area of Science:

• Forensic Toxicology
• Analytical Chemistry
• Pharmacology

Background:

• Distinguishing endogenous from exogenous Gamma-hydroxybutyrate (GHB) in hair is crucial for forensic investigations.
• Existing studies often overlook intra-individual GHB variations by analyzing single hair segments.
• The United Nations Office on Drugs and Crime (UNODC) recommends comparing GHB concentrations to basal levels for verifying intake.

Purpose of the Study:

• To evaluate the relevance of segmental hair analysis for detecting endogenous Gamma-hydroxybutyrate (GHB).
• To assess intra-individual variability of endogenous GHB concentrations in hair segments.
• To validate a new method for endogenous GHB detection in hair.

Main Methods:

• Analysis of hair samples from 200 subjects using a validated LC-MS/MS method.
• Division of hair strands into three 1 cm segments after discarding the proximal 0.5 cm.
• Water extraction performed during pulverization before LC-MS/MS analysis.

Main Results:

• Endogenous GHB concentrations varied from below the limit of detection (< 0.1 ng/mg) to 6.6 ng/mg.
• 27% of samples showed GHB levels below the limit of detection in at least two segments.
• Limited intra-individual variability was observed, though significant variations (> 1 ng/mg) occurred in 4% of cases between segments.
• Hair treatments were found to potentially alter endogenous GHB concentrations.

Conclusions:

• Segmental hair analysis is essential in forensic cases to accurately determine Gamma-hydroxybutyrate (GHB) levels.
• Understanding intra-individual GHB variation is critical for reliable forensic interpretation.
• The validated method provides a robust approach for endogenous GHB detection in segmented hair samples.