Detection of Exogenous GHB in Blood by Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry: Implications in Postmortem Toxicology

• Published in: Journal of analytical toxicology 2005-11, Vol.29 (8), p.777-781
• Main Authors: Saudan, Christophe, Augsburger, Marc, Kintz, Pascal, Saugy, Martial, Mangin, Patrice
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Carbon Isotopes; Drug intoxications. Doping; Forensic Medicine - methods; Gas Chromatography-Mass Spectrometry - methods; Humans; Medical sciences; Pharmacology. Drug treatments; Sodium Oxybate - blood; Substance Abuse Detection - methods
• ISSN: 0146-4760; 1945-2403
• DOI: 10.1093/jat/29.8.777

Because GHB (γ-hydroxybutyrate) is present in both blood and urine of the general population, toxicologists must be able to discriminate between endogenous levels and a concentration resulting from exposure. In this paper, we propose a procedure for the detection of exogenous GHB in blood by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Following liquid-liquid and solid-phase extractions, GHB is derivatized to GHB di-TMS before analysis by GC-C-IRMS. Significant differences in the carbon isotopic ratio (Δδ13C-values > 13.5‰) were found between endogenous and synthetic GHB. Indeed, for postmortem blood samples with different GHB concentrations (range: 13.8–86.3 mg/L), we have obtained GHB δ13C-values ranging from −20.6 to −24.7‰, whereas δ13C-values for the GHB from police seizure were in the range −38.2 to −50.2‰. In contrast to the use of cut-off concentrations for positive postmortem blood GHB concentrations, this method should provide an unambiguous indication of the drug origin.