Beckers J L
Eindhoven University of Technology, Department of Chemistry, The Netherlands.
Electrophoresis. 2001 Aug;22(13):2684-90. doi: 10.1002/1522-2683(200108)22:13<2684::AID-ELPS2684>3.0.CO;2-C.
In electrophoretic processes, often zones migrate through the separation compartment, with a composition different from that of the background electrolyte (BGE) but which do not contain, however, any component of the sample mixture. These zones migrate with a mobility mainly determined by the composition of the BGE and are called system zones (SZs). If these SZs are visible in electropherograms they are called system peaks (SPs). If sample components have a mobility close to that of a SZ, the separation process can be disturbed and the sample peak shapes are deformed. SZs can appear applying BGEs containing more co-ionic species or if BGEs are used at high or low pH. Recently, the existence of SZs has been described applying BGEs containing weak multivalent anionic species. In this paper, the diverse kinds of system zones, are discussed for cationic systems and the effect of invisible SZs on separations is shown. As an example of a weak multivalent cation, the behavior of the divalent cation histamine is studied, which can be used as co-ion in BGEs for the separation of cations in the indirect UV mode. Applying BGEs containing histamine, SZs are visible in the electropherograms and there existence could also be established theoretically by the use of SystCharts. A mathematical model for the calculation of the mobility of SZs is verified and it has been shown that an unsafe region with a mobility window of msp +/- 10% can be indicated, for the separation of fully ionized sample components.
在电泳过程中，常常会有一些区带穿过分离室迁移，其组成与背景电解质（BGE）不同，但不包含样品混合物的任何组分。这些区带的迁移率主要由BGE的组成决定，被称为系统区带（SZs）。如果这些SZs在电泳图中可见，它们就被称为系统峰（SPs）。如果样品组分的迁移率与某个SZ接近，分离过程可能会受到干扰，样品峰的形状也会变形。当使用含有更多共离子物种的BGE或者在高pH或低pH条件下使用BGE时，可能会出现SZs。最近，已经报道了在使用含有弱多价阴离子物种的BGE时存在SZs。本文讨论了阳离子体系中不同种类的系统区带，并展示了不可见SZs对分离的影响。作为弱多价阳离子的一个例子，研究了二价阳离子组胺的行为，它可以在间接紫外模式下用作BGE中的共离子来分离阳离子。使用含有组胺的BGE时，SZs在电泳图中可见，并且通过使用SystCharts理论上也可以确定它们的存在。验证了一个计算SZs迁移率的数学模型，结果表明对于完全电离的样品组分的分离，可以指出一个迁移率窗口为msp +/- 10%的不安全区域。
