Horká M, Slais K
Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic, Brno.
Electrophoresis. 2000 Aug;21(14):2814-27. doi: 10.1002/1522-2683(20000801)21:14<2814::AID-ELPS2814>3.0.CO;2-G.
The asymmetric triangle (fronting or tailing) concentration profiles and their broadening are the typical results of the electromigrational zone dispersion characterizing a system of the analyte in the background electrolyte (BGE). The present contribution suggests the parameter named the relative velocity slope, SBGE,X, which was introduced here as a quantity characterizing the peak broadening and the asymmetry. SBGE,X VS. analyte ionic mobility diagrams are suitable for the comparison of BGEs of given pH and the conductivity composed of electrolytes of different pKaS and ionic mobilities. The concept of SBGE,X diagrams is verified by capillary zone electrophoresis of the model analytes, which involve (i) the series of sulfobenzoylated poly(ethylene glycols) as examples of the strong electrolytes with different ionic mobilities and (ii) the series of monobasic phenols as weak electrolytes with different pKaS and similar ionic mobilities. It follows from both theoretical predictions of peak symmetry and their experimental verification that the optimum composition of BGEs is determined mostly by the suitable ionic mobility of the coion in dependence on the ionic mobility of the analyte. The low-conductivity BGEs based on low-molecular carrier ampholytes are at best only comparable with the properly chosen monobasic electrolytes.
不对称三角形（前沿或拖尾）浓度分布及其展宽是分析物在背景电解质（BGE）体系中电迁移区扩散的典型结果。本文提出了相对速度斜率参数SBGE,X，它作为表征峰展宽和不对称性的量在此处引入。SBGE,X与分析物离子迁移率的关系图适用于比较给定pH值以及由不同pKa和离子迁移率的电解质组成的具有相同电导率的BGE。SBGE,X图的概念通过对模型分析物的毛细管区带电泳得到验证，这些模型分析物包括：（i）一系列磺酰苯甲酰化聚乙二醇，作为具有不同离子迁移率的强电解质的实例；（ii）一系列一元酚，作为具有不同pKa和相似离子迁移率的弱电解质。从峰对称性的理论预测及其实验验证都可以得出，BGE的最佳组成主要取决于共离子的合适离子迁移率与分析物离子迁移率的关系。基于低分子载体两性电解质的低电导率BGE充其量只能与适当选择的一元电解质相媲美。
