Broad-spectrum toxicological analysis of hair based on capillary zone electrophoresis–time-of-flight mass spectrometry

The coupling of capillary electrophoresis–electrospray ionization and time-of-flight mass spectrometry, combining efficiency and speed of separation with high mass accuracy and fast scanning capability, was for the first time applied to the determination of drugs of abuse (amphetamine, methamphetamine, MDA, MDMA, ephedrine, cocaine, morphine, codeine) and their metabolites in hair (6-MAM, benzoylecgonine). Experimental conditions were as follows. Separation: voltage 15 kV, uncoated fused-silica capillary (75 μm ID, 100 cm total length), running electrolyte 25 mM ammonium formate, pH 9.5, field-amplified sample stacking injection. Forensic drugs could be identified by exact mass determination (mass accuracy typically ≤ 5 ppm) and by match of the isotopic pattern. The method was fully validated, showing limit of detections (LODs) suitable for the determination of all the compounds below the cut-off usually adopted for hair analysis (0.1 ng/mg). Analytical precision in real matrices (tested at 0.1 and 1.0 ng/mg) was typically characterized by CVʹs ≤ 24% in both intra-day and day-to-day experiments. Quantitative determination was also tested by using a single internal standard (folcodine). Results, although with a moderate accuracy, conceivably depending on the lack of deuterated internal standards, proved useful for diagnostic use of the results from hair analysis. A single liquid–liquid extraction procedure was applied for all analytes, allowing the detection of a broad spectrum of basic drugs and their major metabolites.