title: Determination of endogenous concentration of γ-hydroxybutyric acid (GHB) in hair through an ad hoc GC-MS analysis: A study on a wide population and influence of gender and age.
abstract: γ-Hydroxybutyric acid (GHB) spread for recreational purposes or as "rape drug" represents a hard issue for forensic toxicologists due to its endogenous nature. It is clear that an actual and reliable discrimination between basal and exogenous levels is mandatory to achieve a correct evaluation of conscious/unconscious administration. This research aimed to study the GHB baseline in hair samples, collected from 150 volunteers, non-consumers of any drugs of abuse, in order to evaluate if a generic cut-off value could be accepted, also focusing on potential influences of gender and age. The analysis consisted of an overnight incubation with NaOH at 56 °C, liquid-liquid extraction with ethylacetate and trimethylsylil derivatization. Detection was carried out through gas chromatography-mass spectrometry in single ion monitoring (m/z 233, 234, 147 for GHB; m/z 239, 240 and 147 for GHB-d6). The endogenous amount in "blank" hair was estimated by the standard addition method. Concentration range was 0.279-2.839 ng/mg. In males, the average GHB levels were higher than in females (0.829 vs 0.596 ng/mg, respectively), especially in the first age category (<30 years, 1.008 vs 0.606 ng/mg, respectively). Age influences on GHB levels seemed to be different among the two sexes: in male population concentrations were higher <30 (1.008 ng/mg) and similar in the other age ranges (0.762 ng/mg, 30-50; 0.763 ng/mg, >50); in female, quite similar levels were registered throughout all the age categories (0.606 ng/mg, <30; 0.536 ng/mg, 30-50; 0.691 ng/mg, >50). Further study should be performed on GHB physiology in order to better understand these differences among ages and genders. Moreover, we demonstrated that for hair analysis a cut-off reference value is not strictly mandatory, underlining the great interpretative valence of segmental analysis.
authors.affiliation: Department of Health Science, Forensic Toxicology Division, University of Florence, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Vaiano
authors.affiliation: Department of Health Science, Forensic Toxicology Division, University of Florence, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Serpelloni
authors.affiliation: Department of Chemistry "U. Schiff", University of Florence, Italy.
authors.forename: Sandra
authors.initials: S
authors.lastname: Furlanetto
authors.affiliation: Department of Health Science, Forensic Toxicology Division, University of Florence, Italy.
authors.forename: Diego
authors.initials: D
authors.lastname: Palumbo
authors.affiliation: Department of Health Science, Forensic Toxicology Division, University of Florence, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Mari
authors.affiliation: Department of Health Science, Forensic Toxicology Division, University of Florence, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Fioravanti
authors.affiliation: Department of Health Science, Forensic Toxicology Division, University of Florence, Italy. Electronic address: elisabetta.bertol@unifi.it.
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Bertol
mesh_terms: D000328:Adult; D000367:Age Factors; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006197:Hair / Q000737:chemistry*; D006801:Humans; D006885:Hydroxybutyrates / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D055815:Young Adult
chemical_list: D006885:Hydroxybutyrates; C111420:4-hydroxybutyric acid
keywords: Age; GHB; GHB cut-off; Gender; Hair