title: Hair testing for cocaine and metabolites by GC/MS: criteria to quantitatively assess cocaine use.
abstract: A simple, rapid and sensitive method has been developed and validated for the determination of cocaine and its main metabolites (benzoylecgonine and cocaethylene) in human hair. The method involved solid-phase extraction with an Oasis HLB extraction cartridge and subsequent analysis by GC/MS. The limit of detection was 0.01 ng mg(-1) for cocaine, 0.04 for benzoylecgonine and 0.03 for cocaethylene. The method validation included linearity (with a correlation coefficient >0.99 over the range 0.2-50 ng mg(-1) ), intra- and inter-day precision (always lower than 12%) and accuracy (mean relative error always below 17%) to meet the bioanalytical acceptance criteria. The procedure was further applied to 40 hair samples from self-reported cocaine users arrested by the police who provided a positive urine-analysis for cocaine, and was demonstrated to be suitable for its application in forensic toxicology. New approaches were raised to detect false-negative results that allow a better interpretation of hair testing results.
authors.affiliation: Department of Legal Medicine and Toxicology, University of Granada School of Medicine, Avda. Madrid, 11, 18071, Granada, Spain. olga@ugr.es
authors.forename: O
authors.initials: O
authors.lastname: López-Guarnido
authors.forename: I
authors.initials: I
authors.lastname: Álvarez
authors.forename: F
authors.initials: F
authors.lastname: Gil
authors.forename: L
authors.initials: L
authors.lastname: Rodrigo
authors.forename: H C
authors.initials: HC
authors.lastname: Cataño
authors.forename: A M
authors.initials: AM
authors.lastname: Bermejo
authors.forename: M J
authors.initials: MJ
authors.lastname: Tabernero
authors.forename: A
authors.initials: A
authors.lastname: Pla
authors.forename: A F
authors.initials: AF
authors.lastname: Hernández
mesh_terms: D003042:Cocaine / Q000031:analogs & derivatives* / Q000302:isolation & purification; D005260:Female; D049429:Forensic Pathology; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006197:Hair / Q000737:chemistry*; D006801:Humans; D057230:Limit of Detection; D008297:Male; D015203:Reproducibility of Results; D052616:Solid Phase Extraction
chemical_list: C005618:benzoylecgonine; C066444:cocaethylene; D003042:Cocaine