Screening and quantitation of forty-six drugs of abuse and toxic compounds in human whole blood by capillary electrophoresis: Application to forensic cases

A novel capillary electrophoresis method, coupled with photo-diode array detection, was established for the analysis of forty-six drugs of abuse, including opiates, cocaine, amphetamines, benzodiazepines, and alkaloids, in human whole blood. Doxapram was used as the internal standard, and an Oasis HLB column was used for solid-phase extraction of drugs from human whole blood. This method was applied to analyze real blood samples in forensic cases. The separation was performed on a fused-silica capillary (75 μm I.D. × 50.2 cm, with 40 cm of effect length). In this study, the running buffer was 150 mM phosphate buffer (pH 2.4) containing 20% methanol. Samples were injected at a pressure of 0.5 psi for 10 s and separated at a running voltage of 16 kV. The precision, accuracy, sensitivity, linear range, limit of detection, and recovery of the method were evaluated. The time taken for the entire separation process was 18.5 min. All compounds were identified by relative retention times, and the peak height ratios (the ratio between the target analyte peak height and the internal standard peak height) were monitored at 200 nm and 210 nm in corresponding ultraviolet spectra. 210 nm was used as quantitative detection wavelength. Calibration curves were established for all compounds of interest. For human blood samples, the detection limits were 8-80 ng/mL, and the linear range was 0.03-10 μg/mL. The intraday and interday precisions were both less than 13%. This method offers simple and effective screening and quantitation of drugs of abuse and toxic compounds in human blood at toxicologically relevant concentrations, and was applied to analyze blood samples from forensic cases.