標題: Determination of cocaine and its metabolites using cation-selective exhaustive injection and sweeping-MEKC
作者: Su, Hsiu-Li
Feng, Lan-Ing
Jen, Hsiu-Ping
Hsieh, You-Zung
應用化學系
Department of Applied Chemistry
關鍵字: Cocaine and its metabolites;CSEI-sweeping-MEKC;On-line preconcentration;Sweeping-MEKC
公開日期: 1-Nov-2008
摘要: We have employed a high-sensitivity on-line preconcentration method, cation-selective exhaustive injection (CSEI) and sweeping MEKC, for the analysis of cocaine, benzoylecgonine, norcocaine, and cocaethylene. We monitored the effects of several of the CSEI-sweeping-MEKC parameters - including the pH, the concentrations of SDS and organic modifier, the injection length of the high-conductivity buffer, and the injection time of the sample - to optimize the separation process. The optimal BGE was 100 mM phosphoric acid (pH 1.8) containing 75 mM SDS with 10% 2-propanol and 10% tetrahydrofuran as the organic modifier. In addition, electrokinetic injection of the sample at 15 kV for 900 s provided both high separation efficiency and enhanced sweeping sensitivity. The sensitivity enhancements for cocaine, norcocaine, and cocaethylene ranged from 2.06 x 10(4) to 3.96 x 10(4); for benzoylecgonine it was 1.75 x 10(3); the coefficients of determination exceeded 0.9958. The LODs, based on an SIN ratio of 3:1, of sweeping-MEKC ranged from 33.5 to 52.8 ng/mL; in contrast, when using CSEI-sweeping-MEKC the sensitivity increased to range from 29.7 to 236 pg/mL. Under the optimal conditions, we analyzed cocaine in a human urine sample prepared using off-line SPE to minimize the influence of the matrix. The recovery of the SPE efficiency was satisfactory (ca. 74.9-87.6%). Our experimental results suggest that, under the optimal conditions, the CSEI-sweeping-MEKC method can be used to determine cocaine and its metabolites with high sensitivity in human urine.
URI: http://dx.doi.org/10.1002/elps.200800167
http://hdl.handle.net/11536/8193
ISSN: 0173-0835
DOI: 10.1002/elps.200800167
期刊: ELECTROPHORESIS
Volume: 29
Issue: 20
起始頁: 4270
結束頁: 4276
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