Optimization of a simple method for the chiral separation of phenethylamines of forensic interest based on cyclodextrin complexation capillary electrophoresis and its preliminary application to the analysis of human urine and hair

Because of the forensic importance of the chiral analysis of amphetamine and other phenethyl amines for investigating their synthetic pathways and the metabolic patterns of these compounds, a capillary electrophoresis method has been developed based on the chiral selectivity of beta-cyclodextrin. The influence of different experimental conditions, such as cyclodextrin nature and concentration, voltage, temperature and buffer concentration and pH, on analytical performance has been studied. The optimized analytical conditions are: capillary: bare fused silica, 50 mu m I.D., 40 cm effective length; buffer: 150 mM phosphate pH=2.5, 15 mM beta-cyclodextrin; voltage: 10 kV; temperature: 17.5 degrees C; detection: UV absorption at 200 nm wavelength. Under these conditions, amphetamine, methamphetamine and ephedrine have been easily separated, with baseline resolution of the respective enantiomers. Sensitivity was better than 300 ng per mi. The average precision of migration times of the three analytes was good with RSD=0.45% and 0.58% in intra-day and day-to-day tests, respectively. Reproducibility of peak heights was also good, with RSD=2.51% and 3.14% in intra-day and day to-day tests, respectively. The preliminary analysis of amphetamine in human urine and hair samples, subjected to a simple work-up procedure based on liquid-liquid extraction, showed clean blank electropherograms, excellent chiral resolution and sensitivity, suitable for the analysis of real samples from amphetamine users. (C) 1997 Elsevier Science Ireland Ltd.