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

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.

Evaluation of buprenorphine LUCIO immunoassay versus GC-MS using urines from a workplace drug testing program.

The buprenorphine (BUP) LUCIO Nal Von Minden screening assay was evaluated. Urine samples from subjects enrolled in a workplace drug testing program were screened according to the manufacturer's instruction using a Roche COBAS Integra 800 analyser. For gas chromatography-mass spectrometry (GC-MS) confirmatory analysis, samples were submitted to enzymatic hydrolysis with ß-glucuronidase and mixed-mode solid-phase extraction. Imprecision (coefficient of variation) for 3.0, 7.0, and 13.0 ng/mL calibrators varied within 2.8-8.7 intra-day (n = 20) and 7.7-8.6 inter-day (n = 19). Inaccuracy (bias) was between -5.6-30.5 intra-day and -13.2-4.2 inter-day. At the 5 ng/mL cut-off, the immunoassay showed 100% sensitivity and 88% specificity, with an overall agreement of 94% between immunoassay and GC-MS. Raising the cut-off to 10 ng/mL provided an identical overall agreement between immunoassay and GC-MS (94%), despite the decrease in sensitivity (90%) and the increase in specificity (100%). According to these results, the BUP LUCIO Nal Von Minden screening assay provides adequate sensitivity and specificity for BUP screening in urine samples using a cut-off concentration of 5 ng/mL.