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On-line stacking and sweeping capillary electrophoresis for detecting heroin metabolites in human urine

Jong, Yuh-Jyh, Ho, Yi-Hui, Ko, Wei-Kung, Wu, Shou-Mei
Journal of chromatography 2009 v.1216 no.44 pp. 7570-7575
capillary electrophoresis, codeine, detection limit, humans, liquid chromatography, liquid-liquid extraction, mass spectrometry, metabolites, methanol, micellar electrokinetic capillary chromatography, morphine, pH, silica, sodium dodecyl sulfate, urine
Heroin metabolites including morphine, codeine, and 6-acetylmorphine were determined by cation-selective exhaustive injection and sweeping micellar electrokinetic chromatography (CSEI-sweep-MEKC). Liquid-liquid extraction was used for urine pretreatment. An uncoated fused silica capillary (Ld=30cm, 50μm ID) was filled with phosphate buffer (50mM, pH 2.5) containing 30% methanol, then high conductivity buffer (100mM phosphate, 41.3kPa for 18s) was followed. Samples were injected electrokinetically (20kV, 300s). The sweeping and separation were performed at −25kV using phosphate buffer (20mM, pH 2.5) and 80mM sodium dodecyl sulfate. The baseline separation was done within 10min. During method validation, the calibration curves were linear over a range of 50-500ng/mL (r ≧0.994). The RSD and RE values in intra-day and inter-day assays were all below 20%, which showed good precision and accuracy. Their detection limits were 10ng/mL (S/N=3). The optimized method was applied to determine real urine samples from addicts. These samples were confirmed by liquid chromatography/mass spectrometry.