Diress Abebaw G, Lucy Charles A
Department of Chemistry, Gunning/Lemieux Chemistry Centre, University of Alberta, Edmonton, Alta., T6G 2G2 Canada.
J Chromatogr A. 2004 Feb 20;1027(1-2):185-91. doi: 10.1016/j.chroma.2003.10.081.
Manipulation of the electroosmotic flow (EOF) is essential for achieving optimized separations of small anions by capillary electrophoresis (CE). In this work, efficient suppression or reversal of EOF is achieved upon addition of small amounts of the cationic surfactants, cetyltrimethylammonium bromide (CTAB) or didodecyldimethylammonium bromide (DDAB) to the electrophoretic buffer. Highly stable and reversed EOF are achieved using the surfactants in the presence of up to 50% MeOH. In aqueous and low methanol containing solutions (up to 30%, v/v) surface aggregation of the surfactants at the capillary wall occurs at a concentration below the critical micelle concentration (CMC). The impact of MeOH on reversed EOF is predominantly a function of the diminished zeta potential of the silica, and to a lesser extent on the CMC in the bulk solution of the surfactant. Fast baseline separation and selectivity changes for small inorganic anions are observed when mixed aqueous-organic buffers are employed. Changes in EOF, micellar properties of the surfactant and selectivity for inorganic anions upon addition of various percent of methanol are also discussed.
电渗流（EOF）的操控对于通过毛细管电泳（CE）实现小阴离子的优化分离至关重要。在这项工作中，向电泳缓冲液中添加少量阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）或二癸基二甲基溴化铵（DDAB），可有效抑制或反转EOF。在高达50%甲醇存在的情况下使用这些表面活性剂可实现高度稳定且反转的EOF。在水相和低甲醇含量（高达30%，v/v）的溶液中，表面活性剂在毛细管管壁上的聚集发生在低于临界胶束浓度（CMC）的浓度下。甲醇对反转EOF的影响主要取决于二氧化硅zeta电位的降低，在较小程度上也取决于表面活性剂本体溶液中的CMC。当使用混合水 - 有机缓冲液时，可观察到小无机阴离子的快速基线分离和选择性变化。还讨论了添加不同百分比甲醇后EOF、表面活性剂的胶束性质以及对无机阴离子选择性的变化。
