Characterization of the cationic surfactant induced reversal of electroosmotic flow in capillary electrophoresis
Characterization of the cationic surfactant induced reversal of electroosmotic flow in capillary electrophoresis
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DOI：
10.1021/ac950632h
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发表时间：
1996-01-15
影响因子：
7.4
通讯作者：
Underhill, RS
中科院分区：
文献类型：
--
作者：
Lucy, CA;Underhill, RS
在毛细管电泳缓冲液中加入阳离子表面活性剂可以抑制电泳中的电渗流。这种逆转是由于在毛细管壁形成双层或半胶束，有效地使壁电荷为正。双层可以通过吸附单体表面活性剂或通过亚胶束（表面活性剂对）形成，这取决于缓冲液的离子强度和毛细管壁的表面电荷。在足以形成双层的阳离子表面活性剂浓度下（即，大于临界胶束浓度）时，电渗流速度与pH值无关，pH值高于4。离子强度的调整导致反向电渗流速率的微小变化，这是由于吸附的表面活性剂的浓度增加和双层厚度减小的相反力。溶液中的阴离子抗衡离子的性质对现在观察到的反向电渗的大小有很强的影响，类似于缓冲液阳离子对正常电渗的影响。这种效果是用一个简单的离子交换模型来解释。
Reversal of electroosmotic now in capillary electrophoresis can be achieved by the addition of cationic surfactants to the electrophoretic buffer. This reversal of now is caused by the formation of a bilayer or hemimicelle at the walls of the capillary, effectively making the wall charge positive, The bilayer can be formed either by adsorption of monomeric surfactants or by admicelles (surfactant pairs), depending on the ionic strength of the buffer and the surface charge at the capillary walls. At concentrations of cationic surfactant sufficient to form the bilayer (i.e., greater than the critical micelle concentration) the electroosmotic now velocity is independent of pH above a pH of 4. Adjustment of the ionic strength causes minor variations in the reversed electroosmotic now rate due to the opposing forces of increased concentration of adsorbed surfactant and decreased double layer thickness. The nature of the anionic counterion in solution has a strong effect on the magnitude of the reversed electroosmotic now observed, analogous to the effect of the buffer cation's effect on normal electroosmotic now. This effect is explained using a simple ion exchange model.