混合固定相电色谱中溶质的输运特征

Transfer of Solutes in Capillary Electrochromatography with Mixed-Mode Stationary Phase

以离子交换和反相固定相构成的混合固定相电色谱中 ,溶质迁移在受到疏水、离子交换作用的同时 ,对于带电溶质而言 ,还受到电泳迁移的影响。根据离子独立迁移原理 ,结合色谱过程中的多种相互作用 ,得到了描述溶质表观迁移速率与其各形态迁移速率、各种相互作用之间相互关系的理论表达式 ;讨论了混合模式电色谱中流动相的 pH及其中的有机调节剂浓度、混合固定相配比等对电渗流的影响及不同形态溶质在柱内的输运特征。结果表明 ,在电色谱中采用混合固定相可以在较大的 pH和有机调节剂浓度范围内得到较强且稳定的电渗流。pH通过改变溶质的形态影响分离 ;有机调节剂对中性溶质的影响满足一般反相电色谱中的规律 ;竞争试剂对带电溶质分离的影响较大 ,它的加入可以有效地改善峰形 ,但是由于电泳作用的调节 。

In capillary electrochromatography with the mixed mode stationary phase, while the transfer of solutes could be controlled by the contributions of chromatography (reversed phase and ion exchange), the transfer of charged solutes could be influenced by electrophoresis transfer. According to the principle of ion independent transfer and several kinds of interaction between solute, mobile phase, and stationary phase, an theoretical expression was derived to describe the relationship among the apparent transfer velocity of solute, the transfer velocities in various forms and the diversified interactions. The studies focused on the influence of various parameters (e.g., pH, organic modifier content, stationary phase proportion) and the transfer characters of various solutes in the mixed-mode capillary electroosmotic chromatography (CEC). These results demonstrate that electroosmotic flow in the mixed stationary phase electrochromatography are kept high and steady within wide ranges of pH and organic modifier content. The separation was affected by the pH through the change of the solutes conformation. The influence of neutral solutes by organic modifier complies with the rule of conventional reversed phase CEC. The separation of charged solutes was influenced evidently by the compete reagents which could improve the shape of the peak, but it was not so important as in the conventional ion exchange chromatography due to the adjustment by the function of electrophoresis.