Electrokinetic processes that lead to pH gradient instabilities in carrier ampholyte‐based IEF are reviewed. In addition to electroosmosis, there are four of electrophoretic nature, namely (i) the stabilizing phase with the plateau phenomenon, (ii) the gradual isotachophoretic loss of carrier ampholytes at the two column ends in presence of electrode solutions, (iii) the inequality of the mobilities of positively and negatively charged species of ampholytes, and (iv) the continuous penetration of carbonate from the catholyte into the focusing column. The impact of these factors to cathodic and anodic drifts was analyzed by simulation of carrier ampholyte‐based focusing in closed and open columns. Focusing under realistic conditions within a 5 cm long capillary in which three amphoteric low molecular mass dyes were focused in a pH 3–10 gradient formed by 140 carrier ampholytes was investigated. In open columns, electroosmosis displaces the entire gradient toward the cathode or anode whereas the electrophoretic processes act bidirectionally with a transition around pH 4 (drifts for pI > 4 and pI < 4 typically toward the cathode and anode, respectively). The data illustrate that focused zones of carrier ampholytes have an electrophoretic flux and that dynamic simulation can be effectively used to assess the magnitude of each of the electrokinetic destabilizing factors and the resulting drift for a combination of these effects. Predicted drifts of focused marker dyes are compared to those observed experimentally in a setup with coated capillary and whole column optical imaging.

中文翻译：

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基于载体两性电解质的等电聚焦中 pH 梯度的不稳定性：通过计算机模拟阐明贡献的电动过程

回顾了导致基于载体两性电解质的 IEF 中 pH 梯度不稳定性的电动过程。除电渗外，还有四种电泳性质，即（i）具有平台现象的稳定相，（ii）在电极溶液存在下，两柱端的载体两性电解质逐渐等速电泳损失，（iii）不等式两性电解质的正电荷和负电荷物质的迁移率，以及（iv）碳酸盐从阴极电解质连续渗透到聚焦柱中。通过模拟封闭和开放柱中基于载体两性电解质的聚焦，分析了这些因素对阴极和阳极漂移的影响。在 5 cm 长毛细管内的实际条件下聚焦，其中三种两性低分子量染料聚焦在由 140 种载体两性电解质形成的 pH 3-10 梯度中。在开放柱中，电渗将整个梯度移向阴极或阳极，而电泳过程双向作用，在 pH 4 附近发生转变（pI > 4 和 pI < 4 通常分别向阴极和阳极漂移）。数据表明，载体两性电解质的聚焦区域具有电泳通量，并且动态模拟可以有效地用于评估每个电动不稳定因素的大小以及这些影响的组合所产生的漂移。