Detection of gamma-hydroxybutyrate in hair: Validation of GC–MS and LC–MS/MS methods and application to a real case

• Published in: Journal of pharmaceutical and biomedical analysis 2012-11, Vol.70, p.518-522
• Main Authors: Bertol, Elisabetta, Argo, Antonina, Procaccianti, Paolo, Vaiano, Fabio, Di Milia, Maria Grazia, Furlanetto, Sandra, Mari, Francesco
• Format: Article
• Language: English
• Subjects: Acetates - chemistry; Adult; Analysis; Analytical, structural and metabolic biochemistry; application methods; Biological and medical sciences; Calibration; Chromatography, Liquid - standards; Crime; derivatization; detection limit; digestion; drugs; ethyl acetate; Forensic Toxicology - methods; Forensic Toxicology - standards; Fundamental and applied biological sciences. Psychology; Gamma-hydroxybutyrate; Gas Chromatography-Mass Spectrometry - standards; gas-chromatography-mass spectrometry; GC–MS; General pharmacology; GHB; Hair; Hair - metabolism; Humans; ionization; ions; LC–MS/MS; Limit of Detection; Linear Models; liquid chromatography; Liquid-Liquid Extraction; Male; Medical sciences; monitoring; Pharmacology. Drug treatments; Quality Control; Reference Standards; Reproducibility of Results; Segmental analysis; sodium hydroxide; Sodium Hydroxide - chemistry; Sodium Oxybate - pharmacokinetics; Spectrometry, Mass, Electrospray Ionization - standards; Street Drugs - legislation & jurisprudence; Street Drugs - pharmacokinetics; Substance Abuse Detection - standards; Substance-Related Disorders - diagnosis; Substance-Related Disorders - metabolism; tandem mass spectrometry; Tandem Mass Spectrometry - standards; Temperature
• ISSN: 0731-7085; 1873-264X
• DOI: 10.1016/j.jpba.2012.07.009

A gas chromatography–mass spectrometry (GC–MS) and a liquid chromatography tandem mass spectrometry (LC–MS/MS) method were validated for quantifying endogenous and exogenous hair concentrations of gamma-hydroxybutyrate (GHB). The GC–MS method is based on overnight extraction of 25mg hair in NaOH at 56°C, liquid/liquid extraction in ethylacetate and trimethylsylil derivatization; analysis is by electron ionization and single ion monitoring of three ions. The LC–MS/MS method entails a rapid digestion of 25mg hair with NaOH at 75°C for 40min, liquid/liquid extraction in ethylacetate and reconstitution of the extract in the LC mobile phase; negative ion electrospray ionization and multiple reaction monitoring (MRM) analysis are employed for the LC–MS/MS detection. In both cases, GHB-d6 is used as an internal standard. The endogenous amount in “blank” hair are estimated by the standard addition method. Limits of detection are 0.4 and 0.5ng/mg for GC–MS and LC–MS/MS respectively, while the limit of quantification (LOQ) is 0.6ng/mg for both methods; the GC–MS method proved to be linear in the range 1–50ng/mg whereas linearity was demonstrated from 0.6 to 50ng/mg for the LC–MS/MS; imprecision and inaccuracy were always lower than 23% for quality controls samples. The two methods were applied to a real case of a man addicted to GHB; the drug concentration in segments from 17cm hair strand well correlated with self-reported use of GHB in different periods of his life. Performances of the two methods were similar.