弛豫理论对离子交换毛细管电色谱中峰压缩现象的研究

 在毛细管电色谱中,由于溶质在输运过程中所具有的电性质,常会产生一些特殊的现象。这些现象,如离子交换毛细管电色谱中产生超高柱效峰的现象,已经不能用一般的色谱理论加以解释。基于弛豫理论所建立的基本模型,在考虑溶质在两相中皆有可能发生正、反向迁移的情况下,得到了流出曲线一阶原点矩和二阶中心矩的理论表达式,并通过对溶质在两相中电扩散速率与电泳速率、电渗流速率关系的分析结果证实:溶质在固定相表面的电扩散行为可以使其保留变弱,出峰加快;而这种电扩散导致的超常柱效峰的出现具有不稳定性,只有在多方面因素综合影响匹配的情况下才可能出现。

A Study on Peak Compression Effect in Ion-Exchange Capillary Electrochromatography with Relaxation Theory

Due to the electric characteristics of the solute transport in capillary electrochromatography (CEC), some special phenomena might occur. An example is the peak compression effect in ion-exchange capillary electrochromatography, which cannot be explained with common chromatography theory. According to the basic model of relaxation theory, it is considered that there are "co-" and "counter-" solute flows in mobile phase and in stationary phase, the expressions of the first moment and the second center moment of profile, and column efficiency are derived by the method of Laplace transform. The relations of electrophoresis velocity, electroosmosis velocity and electric dispersion velocity are also investigated with these expressions. The results show that this new model offers a better explanation for peak compression effect on the migration behaviour of charged solute in CEC. The retention time will be shorter by peak compression effect, which is similar to a solvent gradients process. The peak compression effect is not steady, and (doesn't) appear until the conditions are fitted in some special situation.