Determination of cocaine and metabolites in hair by column-switching LC-MS-MS analysis

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RESEARCH PAPER

Determination of cocaine and metabolites in hair by column-switching LC-MS-MS analysis Marcela Nogueira Rabelo Alves & Gabriele Zanchetti & Alberto Piccinotti & Silvia Tameni & Bruno Spinosa De Martinis & Aldo Polettini

Received: 19 March 2013 / Revised: 1 May 2013 / Accepted: 4 May 2013 / Published online: 24 May 2013 # Springer-Verlag Berlin Heidelberg 2013

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 M. N. R. Alves Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, Ribeirão Preto 14040-903 São Paulo, Brazil G. Zanchetti : A. Piccinotti : S. Tameni Synlab Italia Srl, Via Orzinuovi, 111-25125, Brescia, Italy B. S. De Martinis Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, Ribeirão Preto 14040-901 São Paulo, Brazil A. Polettini (*) Department of Public Health and Community Medicine, University of Verona, P.le Scuro 10, 37134, Verona, Italy e-mail: [email protected]

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. Keywords Column switching . LC-MS-MS . Hair testing . Cocaine and metabolites . Drugs of abuse

Introduction According to the United Nations Office on Drugs and Crime [1], about 230 million people (5 % of the world’s adult population) have used an illicit drug at least once in 2010. Global cocaine (CO) use in the