Gammahydroxybutyrate in hair of non-GHB and repeated GHB users: A new and optimized method Nicolas Van Elsué a, *, Cleo L. Crunelle a,b , Cor A. Verbrugge c , Kim van Baarle c , Anaïs Rodrigues d , Hugo Neels a , Michel Yegles d a Toxicological Center, Antwerp University, Antwerp, Belgium b Vrije Universiteit Brussel (VUB), Universitair Ziekenhuis Brussel (UZ Brussel), Dpt of Psychiatry, Brussels, Belgium c Novadic-Kentron, Network for Addiction Treatment Services, Vught, The Netherlands d Laboratoire National de Santé, Service de Toxicologie, Dudelange, Luxembourg A R T I C L E I N F O Article history: Received 15 May 2018 Received in revised form 19 August 2018 Accepted 20 August 2018 Available online 30 August 2018 Keywords: GHB Hair Method validation Drug abuse Drug testing A B S T R A C T Gamma-hydroxybutyric acid (GHB) is a short-chain fatty acid used recreationally as a drug of abuse due its strong suppressive effect on the central nervous system. The detectionwindow of GHB in blood and urine is very narrow (t1/2 = 30 min) but can be substantially prolonged using alternative matrices such as hair. We here present a newly developed and limited validated method with a solid phase extraction (SPE) using GC–MS/MS to determine concentrations of GHB in hair samples. The soft extraction technique (water and 90 min ultrasonic bath) preserves GHB with a high yield and clean extracts. In addition, endogenous GHB can be detected in hair of non-GHB users. However, little is known about GHB concentrations in hair of abstinent, frequent and chronic GHB users. Therefore, we present data from hair samples of healthy volunteers to evaluate the proposed endogenous GHB ranges, and from GHB-dependent patients to address GHB concentrations in hair with GHB intake. In 20 non-GHB users, a mean endogenous concentration of 1.1  0.6 ng/mg hair (range of 0.3–2 ng/mg) was found. In GHB-dependent patients, concentrations between 6.3–239.6 ng/mg hair were found, with no correlation between concentrations in hair and dose of GHB intake. In summary, we present a new and limited validated method, adequately sensitive for the detection of GHB in hair, as well as first-time measurements of GHB concentrations in dependent patients in order to better understand the relationship between the frequency of use/dose and concentrations observed in hair samples. © 2018 Elsevier B.V. All rights reserved. 1. Introduction Gamma-hydroxybutyric acid (GHB) is a short-chain fatty acid developed in the early 60’s as a synthetic analog to the inhibiting neurotransmitter gamma-amino butyric acid (GABA) [1]. GHB easily crosses the blood-brain barrier, where it binds to the GABA-B receptor complex and strongly suppresses the central nerve system, thereby inducing its sedating effects and addictive properties [1]. GHB, also called liquid-ecstasy, is, however, not related to the ecstasy class (like methylenedioxyamphetamine (MDA) or methylenedioxymethamphetamine (MDMA)). Its effects rather correspond with GABA-mimetics like alcohol and benzo- diazepines [2]. Being easily accessible and at a low cost, GHB was adopted by the nightlife scene for its various properties including increased feelings of euphoria and relaxation, being more social, increased sexuality and creating an altered state of consciousness [3]. Besides being used recreationally as a drug of abuse, GHB is also used in Drug Facilitated Crimes (DFC’s) or Drug Facilitated Sexual Assaults (DFSA’s). Overdose leads to loss of consciousness, deep coma with postural apshyxia, respiratory depression, amnesia and loss of motor control. In very small amounts, GHB is also present endogenously in the mammal brain, where it is synthetized from GABA, but its specific function remains largely unknown. Measuring GHB concentrations in blood and urine is useful to objectify GHB use in GHB-dependent patients or to determine if GHB was administered as a raping drug for legal purposes. After intake, GHB reaches maximal plasma concentrations within 30–50 min [1]. However, detection in blood and urine has a narrow time-window (e.g., hours) due to GHB’s fast metabolization by the liver to H 2 O and CO 2 [1]. Therefore, samples taken long after exposure will often be negative. DFC’s are therefore difficult to prove if blood or urine samples are not taken within the next 3–10 h [1]. For the purpose of detecting long-term or retrospective use, hair analysis is potentially much more interesting. GHB enters the hair partly through deposit * Corresponding author at: Toxicological Center, Antwerp University, Universi- teitsplein 1, 2610 Wilrijk (Antwerp), Belgium. E-mail address: nicovanelsue@gmail.com (N. Van Elsué). https://doi.org/10.1016/j.forsciint.2018.08.025 0379-0738/© 2018 Elsevier B.V. All rights reserved. Forensic Science International 291 (2018) 193–198 Contents lists available at ScienceDirect Forensic Science International journal homepage: www.elsevier.com/locat e/f orsciint