Endogenous γ-hydroxybutyric acid concentrations in saliva determined by gas chromatography-mass spectrometry

Endogenous γ-hydroxybutyric acid (GHB) concentrations in blood and urine are well documented, but there are very little data on natural levels in saliva, a biological matrix increasingly used for drug testing. We measured endogenous GHB concentrations in 120 unpaid volunteers who also provided anonymous epidemiological data. Samples were analyzed using a rapid and reliable method, utilizing liquid-liquid extraction, silyl-derivatization, and gas chromatographic-mass spectrometric analysis. One sample, between the lower limit of quantitation (0.2 mg/L) and limit of detection (0.1 mg/L), was split to 0.15 mg/L for statistical purposes. Salivary GHB concentrations ranged from 0.15 to 3.33 mg/L (mean = 1.29; median = 1.13). Statistical analysis using the Mann-Whitney test indicated that endogenous GHB concentrations in saliva were not significantly affected by age, gender, medical conditions, use of medications, and recent food/drink consumption. Interpreting GHB concentrations in biological samples poses difficulties because of its endogenous presence and rapid elimination, and this is true for saliva as well as blood and urine. However, saliva has the merit of being easy to collect by law enforcement personnel.