Durkin D, Foley J P
Department of Chemistry, Drexel University, Philadelphia, PA 19104, USA.
Electrophoresis. 2000 Jun;21(10):1997-2009. doi: 10.1002/1522-2683(20000601)21:10<1997::AID-ELPS1997>3.0.CO;2-L.
The concept of dual opposite injection in capillary electrophoresis (DOI-CE) for the simultaneous separation, under conditions of suppressed electroosmotic flow, of anionic and cationic compounds with no bias in resolution and analysis time, is extended to a higher pH range in a zone electrophoresis mode (DOI-CZE). A new DOI-CE separation mode based on electrokinetic chromatography is also introduced (DOI-EKC). Whereas conventional CZE and DOI-CZE are limited to the separation of charged compounds with different electrophoretic mobilities, DOI-EKC is shown to be capable of separating compounds with the same or similar electrophoretic mobilities. In contrast to conventional EKC with charged pseudostationary phases that often interact too strongly with analytes of opposite charge, the neutral pseudostationary phases appropriate for DOI-EKC are simultaneously compatible with anionic and cationic compounds. This work describes two buffer additives that dynamically suppress electroosmotic flow (EOF) at a higher pH (6.5) than in a previous study (4.4), thus allowing DOI-CZE of several pharmaceutical bases and weakly acidic positional isomers. Several DOI-EKC systems based on nonionic (10 lauryl ether, Brij 35) or zwitterionic (SB-12, CAS U) micelles, or nonionic vesicles (Brij 30) are examined using a six-component test mixture that is difficult to separate by CZE or DOI-CZE. The effect of electromigration dispersion on peak shape and efficiency, and the effect of surfactant concentration on retention, selectivity, and efficiency are described.
在毛细管电泳中，双相反向进样（DOI-CE）的概念是在抑制电渗流的条件下，同时分离阴离子和阳离子化合物，且在分离度和分析时间上无偏差。该概念已扩展到区带电泳模式（DOI-CZE）的更高pH范围。还引入了一种基于电动色谱的新型DOI-CE分离模式（DOI-EKC）。传统的CZE和DOI-CZE仅限于分离具有不同电泳迁移率的带电化合物，而DOI-EKC已被证明能够分离具有相同或相似电泳迁移率的化合物。与带有电荷的假固定相的传统EKC不同，后者通常与相反电荷的分析物相互作用过强，而适用于DOI-EKC的中性假固定相同时与阴离子和阳离子化合物兼容。本文描述了两种缓冲添加剂，它们能在比先前研究（pH 4.4）更高的pH（6.5）下动态抑制电渗流（EOF），从而实现几种药物碱和弱酸性位置异构体的DOI-CZE。使用六种组分的测试混合物对基于非离子（月桂醇聚醚10，Brij 35）或两性离子（SB-12，CAS U）胶束或非离子囊泡（Brij 30）的几种DOI-EKC系统进行了研究，该测试混合物用CZE或DOI-CZE难以分离。描述了电迁移扩散对峰形和柱效的影响，以及表面活性剂浓度对保留、选择性和柱效的影响。
