Evaluating Endogenous GHB Variation in Hair with a Synthetic Hair Matrix

Area of Science:

• Forensic Toxicology
• Analytical Chemistry
• Biomarker Analysis

Background:

• Accurate quantification of endogenous substances in biological matrices is crucial for forensic and clinical toxicology.
• Human head hair analysis offers a long-term window for detecting drug and metabolite exposure.
• Gamma-hydroxybutyric acid (GHB) is an endogenous substance with potential as a biomarker, but its analysis in hair presents challenges.

Purpose of the Study:

• To develop and validate a quantitative method for endogenous gamma-hydroxybutyric acid (GHB) in human head hair.
• To introduce and evaluate a novel synthetic hair matrix (SMx™ hair) as a calibrator for GHB analysis.
• To assess the variability of endogenous GHB concentrations in human head hair among non-drug users.

Main Methods:

• A synthetic hair matrix (SMx™ hair) was utilized as a calibrator for endogenous GHB.
• A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was validated for GHB quantification in human head hair.
• Validation parameters included accuracy, precision, LOD, LOQ, and stability over a range of 0.4–12 ng/mg.

Main Results:

• The synthetic hair matrix provided a reliable, batch-consistent calibrator without endogenous GHB.
• The validated LC-MS/MS method demonstrated excellent performance with LOD and LOQ at 0.4 ng/mg.
• Analysis of 22 non-GHB users revealed minimal variability in endogenous GHB concentrations across different hair locations and repeat sampling.

Conclusions:

• The synthetic hair matrix is a suitable and effective calibrator for endogenous GHB analysis in human head hair.
• The validated LC-MS/MS method provides accurate and precise quantification of GHB in hair.
• This study establishes a reliable methodology for assessing endogenous GHB levels in hair, with implications for biomarker research.