Beckers J L
Eindhoven University of Technology, Department of Chemistry (SPO), The Netherlands.
Electrophoresis. 2000 Aug;21(14):2788-96. doi: 10.1002/1522-2683(20000801)21:14<2788::AID-ELPS2788>3.0.CO;2-L.
A sample stacking procedure to which a specific combination of electrolyte solutions is applied is isotachophoresis (ITP) superimposed on capillary zone electrophoresis (CZE), a so-called ITP/CZE system. In ITP/CZE some components migrate in an ITP fashion on top of a background electrolyte, and the other analytes migrate in a zone electrophoretic manner. For such a system, the leading electrolyte consists of a mixture of an ionic species, L1, of high mobility (the leading ion of the ITP system), an ionic species, L2, of low mobility (the coions of the CZE system), and a buffering counter-ionic species, whereas the terminating solution only contains the ionic species L2 and the buffering counterions. The zones of the components migrating in the ITP/CZE mode are sharp owing to the self-correcting properties of the zones and the concentrations of the L1 ions of the system. Mobility windows can be calculated, indicating which ions can migrate in the ITP/CZE mode. In this article mobility windows are calculated by applying both strong and weak acids as L1 and L2 ions and it appears that mobility windows can be optimized by chosing different ratios of L1 and L2 as well as different pH values. It is possible to construct very narrow mobility windows, and thereby choose which component of a sample solution can be concentrated, and to what concentration, in a very selective way. The big advantage of ITP/CZE compared with applications such as transient ITP and transient stacking is that the stacked sample ionic species migrate in the ITP mode during the whole experiment; furthermore, they do not destack. Experimentally obtained electropherograms validate the calculated mobility windows for the ITP/CZE mode.
一种应用特定电解质溶液组合的样品堆积方法是等速电泳（ITP）叠加在毛细管区带电泳（CZE）上，即所谓的ITP/CZE系统。在ITP/CZE中，一些组分以ITP方式在背景电解质之上迁移，而其他分析物以区带电泳方式迁移。对于这样一个系统，前导电解质由高迁移率的离子物种L1（ITP系统的前导离子）、低迁移率的离子物种L2（CZE系统的共离子）和缓冲反离子物种的混合物组成，而终止溶液仅包含离子物种L2和缓冲反离子。由于区带的自校正特性和系统中L1离子的浓度，以ITP/CZE模式迁移的组分的区带很尖锐。可以计算迁移率窗口，以表明哪些离子可以以ITP/CZE模式迁移。在本文中，通过应用强酸和弱酸作为L1和L2离子来计算迁移率窗口，结果表明，通过选择不同的L1和L2比例以及不同的pH值，可以优化迁移率窗口。有可能构建非常窄的迁移率窗口，从而以非常有选择性的方式选择样品溶液中的哪些组分可以被浓缩以及浓缩到何种浓度。与诸如瞬态ITP和瞬态堆积等应用相比，ITP/CZE的一大优势在于，堆积后的样品离子物种在整个实验过程中以ITP模式迁移；此外，它们不会解堆积。实验获得的电泳图验证了ITP/CZE模式下计算出的迁移率窗口。
