Determination of GHB in human hair by HPLC-MS/MS: Development and validation of a method and application to a study group and three possible single exposure cases.

Gamma-hydroxybutyrate (GHB) over the last two decades has generated increased notoriety as a euphoric and disinhibitingdrug of abuse in cases of drug-related sexual assault and for this reason it is considered a ‘date rape’ drug.The first aim of this paper was to develop and fully validate a method for the detection of GHB in human hair by highperformance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) after liquid-liquid extraction (LLE).The second aim was the application of the method to hair samples of 30 GHB-free users in order to determine the basallevel. The results obtained showed no significant differences in endogenous concentrations (p = 0.556) between hair samplesof the three groups (black, blonde, and dyed hair) and the age and sex of the subjects did not affect the endogenous levels.Another 12 healthy volunteers, with no previous history of GHB use, were selected and a single dose (25 mg/Kg) was orallyadministered to all of them and hair samples were collected before the administration of the single dose and other two sam-ples were collected one month and two months later, respectively. The segmental analysis of the latter two samples allowedus to calculate two ratios: 4.45:1 (95% C.I. 3.52–5.63) and 3.35:1 (95% C.I. 2.14–5.18), respectively, which can be recommendedas reasonable values for a positive identifi cation of GHB intake.