{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,19]],"date-time":"2025-10-19T15:38:03Z","timestamp":1760888283319,"version":"build-2065373602"},"reference-count":26,"publisher":"Wiley","issue":"20","license":[{"start":{"date-parts":[[2008,10,15]],"date-time":"2008-10-15T00:00:00Z","timestamp":1224028800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Electrophoresis"],"published-print":{"date-parts":[[2008,11]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>We have employed a high\u2010sensitivity on\u2010line preconcentration method, cation\u2010selective exhaustive injection (CSEI) and sweeping MEKC, for the analysis of cocaine, benzoylecgonine, norcocaine, and cocaethylene. We monitored the effects of several of the CSEI\u2010sweeping\u2010MEKC parameters \u2013 including the pH, the concentrations of SDS and organic modifier, the injection length of the high\u2010conductivity buffer, and the injection time of the sample \u2013 to optimize the separation process. The optimal BGE was 100\u2009mM phosphoric acid (pH 1.8) containing 75\u2009mM SDS with 10% 2\u2010propanol and 10% tetrahydrofuran as the organic modifier. In addition, electrokinetic injection of the sample at 15\u2009kV for 900\u2009s provided both high separation efficiency and enhanced sweeping sensitivity. The sensitivity enhancements for cocaine, norcocaine, and cocaethylene ranged from 2.06\u00d710<jats:sup>4<\/jats:sup> to 3.96\u00d710<jats:sup>4<\/jats:sup>; for benzoylecgonine it was 1.75\u00d710<jats:sup>3<\/jats:sup>; the coefficients of determination exceeded 0.9958. The LODs, based on an <jats:italic>S<\/jats:italic>\/<jats:italic>N<\/jats:italic> ratio of 3:1, of sweeping\u2010MEKC ranged from 33.5 to 52.8\u2009ng\/mL; in contrast, when using CSEI\u2010sweeping\u2010MEKC the sensitivity increased to range from 29.7 to 236\u2009pg\/mL. Under the optimal conditions, we analyzed cocaine in a human urine sample prepared using off\u2010line SPE to minimize the influence of the matrix. The recovery of the SPE efficiency was satisfactory (<jats:italic>ca<\/jats:italic>. 74.9\u201387.6%). Our experimental results suggest that, under the optimal conditions, the CSEI\u2010sweeping\u2010MEKC method can be used to determine cocaine and its metabolites with high sensitivity in human urine.<\/jats:p>","DOI":"10.1002\/elps.200800167","type":"journal-article","created":{"date-parts":[[2008,10,15]],"date-time":"2008-10-15T03:23:32Z","timestamp":1224041012000},"page":"4270-4276","source":"Crossref","is-referenced-by-count":24,"title":["Determination of cocaine and its metabolites using cation\u2010selective exhaustive injection and sweeping\u2010MEKC"],"prefix":"10.1002","volume":"29","author":[{"given":"Hsiu\u2010Li","family":"Su","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lan\u2010Ing","family":"Feng","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hsiu\u2010Ping","family":"Jen","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"You\u2010Zung","family":"Hsieh","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2008,11,7]]},"reference":[{"key":"e_1_2_6_2_2","first-page":"186","volume-title":"Disposition of Toxic Drugs and Chemicals in Man","author":"Baselt R. 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