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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.

A method for the rapid and robust confirmation of 11-nor-∆9-tetrahydrocannabinol-9-carboxylic acid (THCA) in urine involving basic hydrolysis with NaOH and direct injection of the hydrolysate in a column-switching LC-MS-MS system was developed and validated. THCA-d3 was used as internal standard. Detection was performed in negative-ion mode by monitoring the transitions from the [M-CO(2) ]- ion m/z 299.2→245.2 and and m/z 299.2→191.1 that were found to provide a better signal-to-noise ratio than the transition from the pseudomolecular ion at m/z 343. The high sensitivity of detection enabled the injection of a small volume (10 µl) of the NaOH hydrolysate which, together with the applied column switching system, proved to confer ruggedness to the method and to avoid the deterioration of the instrumental apparatus despite the large amount of inorganic ions in the hydrolysate. The LLOQ was established at 5 ng/ml, and the LLOD was calculated as 0.2 ng/ml (S/N =3). The method was submitted to thorough validation including evaluation of the calibration range (5-500 ng/ml), accuracy and precision, matrix effects, overall process efficiency, autosampler stability, carryover and cross-talk, and 10-times reduction of sample volume (0.1 ml). Proof of applicability was obtained by direct comparison with the reference GC-MS method in use in the lab (the R(2) between the two methods was 0.9951).

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The authors should like to call your attention to the fact that unfortunately the following acknowledgment was mistakenly omitted in the published article: "The main author (Marcela Nogueira Rabelo Alves) was financially supported by a CNPq´s scholarship (201968/2012-6).