title: Detection of gamma-hydroxybutyrate in hair: validation of GC-MS and LC-MS/MS methods and application to a real case.
abstract: 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 25 mg 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 25 mg hair with NaOH at 75 °C for 40 min, 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 0.5 ng/mg for GC-MS and LC-MS/MS respectively, while the limit of quantification (LOQ) is 0.6 ng/mg for both methods; the GC-MS method proved to be linear in the range 1-50 ng/mg whereas linearity was demonstrated from 0.6 to 50 ng/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 17 cm hair strand well correlated with self-reported use of GHB in different periods of his life. Performances of the two methods were similar.
authors.affiliation: Forensic Toxicology Division, Institute of Legal Medicine, University of Florence, Italy. elisabetta.bertol@unifi.it
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Bertol
authors.forename: Antonina
authors.initials: A
authors.lastname: Argo
authors.forename: Paolo
authors.initials: P
authors.lastname: Procaccianti
authors.forename: Fabio
authors.initials: F
authors.lastname: Vaiano
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Di Milia
authors.forename: Sandra
authors.initials: S
authors.lastname: Furlanetto
authors.forename: Francesco
authors.initials: F
authors.lastname: Mari
mesh_terms: D000085:Acetates / Q000737:chemistry; D000328:Adult; D002138:Calibration; D002853:Chromatography, Liquid / Q000592:standards; D003415:Crime; D053593:Forensic Toxicology / Q000379:methods* / Q000592:standards; D008401:Gas Chromatography-Mass Spectrometry / Q000592:standards; D006197:Hair / Q000378:metabolism*; D006801:Humans; D013287:Illicit Drugs / Q000331:legislation & jurisprudence / Q000493:pharmacokinetics*; D057230:Limit of Detection; D016014:Linear Models; D059625:Liquid-Liquid Extraction; D008297:Male; D011786:Quality Control; D012015:Reference Standards; D015203:Reproducibility of Results; D012972:Sodium Hydroxide / Q000737:chemistry; D012978:Sodium Oxybate / Q000493:pharmacokinetics*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000592:standards; D015813:Substance Abuse Detection / Q000592:standards; D019966:Substance-Related Disorders / Q000175:diagnosis* / Q000378:metabolism; D053719:Tandem Mass Spectrometry / Q000592:standards; D013696:Temperature
chemical_list: D000085:Acetates; D013287:Illicit Drugs; D012972:Sodium Hydroxide; C007650:ethyl acetate; D012978:Sodium Oxybate