title: Determination of cocaine and metabolites in hair by column-switching LC-MS-MS analysis.
abstract: A method for rapid, selective, and robust determination of cocaine (CO) and metabolites in 5-mg hair samples was developed and fully validated using a column-switching liquid chromatography-tandem mass spectrometry system (LC-MS-MS). Hair samples were decontaminated, segmented, incubated overnight in diluted HCl, and centrifuged, and the diluted (1:10 with distilled water) extracts were analyzed in positive ionization mode monitoring two reactions per analyte. Quantifier transitions were: m/z 304.2→182.2 for CO, m/z 290.1→168.1 for benzoylecgonine (BE), and m/z 318.2→196.2 for cocaethylene (CE). The lower limit of quantification (LLOQ) was set at 0.05 ng/mg for CO and CE, and 0.012 ng/mg for BE. Imprecision and inaccuracy at LLOQ were lower than 20 % for all analytes. Linearity ranged between 0.05 and 50.0 ng/mg for CO and CE and 0.012 and 12.50 ng/mg for BE. Selectivity, matrix effect, process efficiency, recovery, carryover, cross talk, and autosampler stability were also evaluated during validation. Eighteen real hair samples and five samples from a commercial proficiency testing program were comparatively examined with the proposed multidimensional chromatography coupled with tandem mass spectrometry procedure and our reference gas chromatography coupled to mass spectrometry (GC-MS) method. Compared with our reference GC-MS method, column-switching technique and the high sensitivity of the tandem mass spectrometry detection system allowed to significantly reduce sample amount (×10) with increased sensitivity (×2) and sample throughput (×4), to simplify sample preparation, and to avoid that interfering compounds and ions impaired the ionization and detection of the analytes and deteriorate the performance of the ion source.
authors.affiliation: Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Marcela Nogueira Rabelo
authors.initials: MN
authors.lastname: Alves
authors.forename: Gabriele
authors.initials: G
authors.lastname: Zanchetti
authors.forename: Alberto
authors.initials: A
authors.lastname: Piccinotti
authors.forename: Silvia
authors.initials: S
authors.lastname: Tameni
authors.forename: Bruno Spinosa
authors.initials: BS
authors.lastname: De Martinis
authors.forename: Aldo
authors.initials: A
authors.lastname: Polettini
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003042:Cocaine / Q000737:chemistry* / Q000378:metabolism; D006197:Hair / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D012680:Sensitivity and Specificity; D015813:Substance Abuse Detection / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D003042:Cocaine