Ultra-rapid procedure to test for γ-hydroxybutyric acid in blood and urine by gas chromatography–mass spectrometry

Gamma-hydroxybutyric acid (GHB) is a substance naturally present within mammal species. Properties of a neurotransmitter or neuromodulator are generally suggested for this substance. GHB is therapeutically used as an anaesthetic, but can be used for criminal offences (date-rape drug). It appears that the window of detection of GHB is very short in both blood and urine, and therefore its presence is very difficult to prove after a rape case. Twenty μl of blood or urine were pipetted into a glass tube, followed by 20 μl GHB-d6 and 45 μl acetonitrile. After vortexing and efficient centrifugation, the supernatant was collected and evaporated to dryness. The residue was derivatized with BSTFA+1% TMCS for 20 min at 70 °C. After injection on a 30-m HP5 MS capillary column, GHB (m/z 233, 204 and 147) and GHB-d6 (m/z 239) were identified by mass spectrometry. The procedure was linear from 1 to 200 mg/l for both blood and urine. Precisions were in the range 4 to 11%. The method appears simple, specific and rapid as an accurate result can be obtained within 1 h.