Lu B, Westerlund D
Analytical Pharmaceutical Chemistry, Uppsala University, Biomedical Center, Sweden.
Electrophoresis. 1998 Jul;19(10):1683-90. doi: 10.1002/elps.1150191027.
Capillary zone electrophoresis with indirect UV-detection was used to separate mixtures containing both positively and negatively charged species. In order to understand the dependence of detector response patterns on the changes in compositions of the background electrolytes and the charge of marker ions (UV-absorbing ions), the separations were performed in two different systems. In a three-ion system (analyte ion, coion and counterion) a marker ion was the major ionic component of a buffer solution and in a two-coion or counterion system the marker ion was used as an additive. In the three-ion system the response profile of an analyte was in good agreement with the mathematical treatment based on the Kohlrausch regulation function. In the two-coion or counterion system the response patterns were more complicated; however, the experimental results agree well with data obtained from a computer simulation program. Peak directions of the analytes were not only determined by their relative charge to the marker ion, but were also associated with their relative mobilities to the buffer coion and the marker ion. The analytes with higher effective mobilities compared to the marker ion were detected as positive peaks and the ones with lower effective mobilities as negative peaks. Similarly to the three-ion system, the detector response of an analyte was stronger by applying a marker coion compared to a counterion. An interesting result was obtained in the separation of a mixture of quaternary ammonium ions and sugars by using a cationic marker ion. The highest and most symmetrical peak was not a cation, but raffinose anion, which appeared most closely to the system peak. The observation suggests that the electromigration dispersion in its zone was eliminated by migrating close to the electroosmosis. A system peak with the mobility corresponding to the electroosmotic flow was obtained in both systems, and an additional system peak with a mobility close to that the marker ion was present in the systems using marker ions as additives.
采用间接紫外检测的毛细管区带电泳法分离含有带正电和带负电物质的混合物。为了了解检测器响应模式对背景电解质组成变化以及标记离子（紫外吸收离子）电荷的依赖性，在两种不同的系统中进行了分离。在三离子系统（分析物离子、同离子和反离子）中，标记离子是缓冲溶液的主要离子成分，而在双同离子或反离子系统中，标记离子用作添加剂。在三离子系统中，分析物的响应曲线与基于科尔劳施调节函数的数学处理结果吻合良好。在双同离子或反离子系统中，响应模式更为复杂；然而，实验结果与计算机模拟程序获得的数据吻合良好。分析物的峰方向不仅取决于它们相对于标记离子的相对电荷，还与它们相对于缓冲同离子和标记离子的相对迁移率有关。与标记离子相比具有较高有效迁移率的分析物被检测为正峰，而具有较低有效迁移率的分析物被检测为负峰。与三离子系统类似，与反离子相比，使用标记同离子时分析物的检测器响应更强。在用阳离子标记离子分离季铵离子和糖的混合物时获得了一个有趣的结果。最高且最对称的峰不是阳离子，而是棉子糖阴离子，它出现得最接近系统峰。该观察结果表明，通过靠近电渗迁移消除了其区域中的电迁移扩散。在两个系统中都获得了迁移率对应于电渗流的系统峰，并且在使用标记离子作为添加剂的系统中存在迁移率接近标记离子的额外系统峰。
