title: Validation of ELISA screening and LC-MS/MS confirmation methods for cocaine in hair after simple extraction.
abstract: This article describes an easy and innovative extraction procedure for cocaine and its primary metabolite, benzoylecgonine (BE), from hair consisting of sonication with H(2)O/0.1% formic acid for 4 h. The same extract was used for screening with an enzyme-linked immunoassay (ELISA) and confirmation by liquid chromatography-tandem mass spectrometry (LC-MS/MS). For the ELISA screening test a cutoff of 0.5 ng/mg was used according to the Society of Hair Testing recommendations. LC-MS/MS limits of detection (LODs) were established to be 10 pg/mg and 1 pg/mg for cocaine and BE, respectively. Linearity was obtained over a range of 0.2-5 ng/mg for BE (target analyte) in the ELISA screening test, while in the LC-MS/MS method the range was 0.10-10 ng/mg for cocaine and 0.01-10 ng/mg for BE. Intra- and interbatch coefficients of variation and mean relative errors were less than 20% for all analytes and concentrations studied. The validated ELISA and LC-MS/MS methods were applied to 48 hair samples and the results of both methods were compared; ELISA demonstrated a sensitivity and specificity of 89.2% and 10.8%.
authors.affiliation: Institute of Legal Medicine, Faculty of Medicine, University of Santiago de Compostela, San Francisco, s/n, 15782 Santiago de Compostela, Spain.
authors.forename: P
authors.initials: P
authors.lastname: López
authors.forename: S
authors.initials: S
authors.lastname: Martello
authors.forename: A M
authors.initials: AM
authors.lastname: Bermejo
authors.forename: Eleonora
authors.initials: E
authors.lastname: De Vincenzi
authors.forename: M J
authors.initials: MJ
authors.lastname: Tabernero
authors.forename: M
authors.initials: M
authors.lastname: Chiarotti
mesh_terms: D000328:Adult; D002853:Chromatography, Liquid; D003042:Cocaine / Q000031:analogs & derivatives / Q000032:analysis*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006197:Hair / Q000737:chemistry*; D006801:Humans; D008297:Male; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry; D055815:Young Adult
chemical_list: D003042:Cocaine