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Enhancement of selectivity and resolution in chiral separation by capillary electrophoresis in aqueous and nonaqueous media.

机译：在水和非水介质中通过毛细管电泳提高手性分离的选择性和分离度。

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摘要

The purpose of the research has been to obtain a fundamental understanding of chiral separation in nonaqueous capillary electrophoresis (NACE), and to enhance chiral selectivity and resolution in both aqueous and nonaqueous media by capillary electrophoresis. This goal is achieved by the alternation of separation solvents, the type of chiral selectors, the charges of solutes, and/or the direction of electroosmotic flow (EOF).; The first part of the research involves a fundamental study of chiral separation using cyclodextrins (CDs) in pure organic solvents, such as formamide (FA), and its derivatives. The results of chiral separation of some hydrophobic amines in three organic solvents, FA, N-methylformamide (NMF), and N,N-dimethylformamide (DMF), were compared to those in pure water and in 6 M urea water systems. The measured binding constants between the solutes and {dollar}beta{dollar}-CD decreased systematically from {dollar}sim 10sp4{dollar} to {dollar}sim10sp{lcub}-2{rcub}{dollar} in the following five systems: water, 6 M urea in water, FA, NMF, and DMF. The decrease in the binding constants results from the decrease in the polarity of the separation solvents. It was also found that in addition to the type and the concentration of CDs, other experimental parameters, such as apparent pH (pH*), ionic strength, temperature, and addition of tetraalkylammonium (TAA{dollar}sp+{dollar}) cations, can also affect separation selectivity and resolution. The application of charged {dollar}beta{dollar}-CDs to separate opposite charged analytes in FA showed that stronger binding between analytes and the opposite charged CD existed due to the additional electrostatic attractions. Compared to aqueous CE chiral separation of analytes with opposite charged CDs, the separation efficiency of the same type of application in FA was higher because peak tailing caused by electrodispersion was not as severe as in the aqueous CE. Enhanced efficiencies were observed at higher ionic strength due to reduction of mobility mismatch between the CD-analyte complexes and the co-ions in the buffer electrolytes. The first application of NACE chiral separation of a commercially available chiral drug, Actron, was also reported in FA by using a quaternary ammonium {dollar}beta{dollar}-CD.; The second part of the research involved the enhancement of chiral selectivity and/or resolution in aqueous media. The application of opposite charged CDs is very useful for the separation of compounds that interact weakly with neutral CDs (such as acebutolol, metanephrine, and normetanephrine, et al.), and the electrodispersion is not a server problem even at the high anionic CD concentrations. For amines that interact strongly with neutral CDs, the change in the compound charges from positive into neutral can eliminate electrodispersion. Thus, the separation efficiency can be enhanced. Finally, the enhancement of resolution by the counter-EOF setup makes it possible to separate enantiomers by the same charged CDs although the separation selectivity between enantiomers and the same charged CDs is likely to be smaller than that between enantiomers and opposite charged CDs.
机译：该研究的目的是获得对非水毛细管电泳（NACE）中手性分离的基本了解，并通过毛细管电泳增强在水和非水介质中的手性选择性和分离度。通过改变分离溶剂，手性选择剂的类型，溶质的电荷和/或电渗流的方向（EOF）来实现该目标。研究的第一部分涉及在纯有机溶剂（例如甲酰胺（FA））及其衍生物中使用环糊精（CD）进行手性分离的基础研究。比较了在三种有机溶剂FA，N-甲基甲酰胺（NMF）和N，N-二甲基甲酰胺（DMF）中某些疏水性胺的手性分离结果与纯水和6 M尿素水系统中的手性分离结果。在以下五个系统中，测得的溶质与{dollar}β{dollar} -CD之间的结合常数从{dollar} sim 10sp4 {dollar}逐渐降低到{dollar} sim10sp {lcub} -2 {rcub} {dollar}：水，水中的6 M尿素，FA，NMF和DMF。结合常数的降低归因于分离溶剂的极性的降低。还发现，除了CD的类型和浓度外，其他实验参数，例如表观pH（pH *），离子强度，温度和四烷基铵（TAA {dollar} sp + {dollar}）阳离子的添加​​，也会影响分离的选择性和分离度。将带电的{beta} {dollar} -CD用于分离FA中相反的带电分析物表明，由于额外的静电吸引，分析物与相反带电的CD之间存在更强的结合力。与带有相反电荷CD的分析物的水相手性水相分离相比，FA中相同类型应用的分离效率更高，因为电分散引起的峰拖尾不像水相中CE那样严重。由于减少了CD-分析物配合物和缓冲液电解质中的共离子之间的迁移率失配，在较高的离子强度下观察到了更高的效率。还报道了在FA中通过使用季铵{美元}β{美元} -CD在商业上可得的手性药物Actron的NACE手性分离的首次应用。研究的第二部分涉及在水性介质中手性选择性和/或拆分度的提高。带有相反电荷的CD的应用对于分离与中性CD弱相互作用的化合物（例如醋丁洛尔，间肾上腺素和去甲肾上腺素等）非常有用，即使在高阴离子CD浓度下，电分散也不是服务器问题。对于与中性CD强烈相互作用的胺，化合物电荷从正电荷变为中性电荷可消除电分散。因此，可以提高分离效率。最后，尽管对映体和相同的带电CD之间的分离选择性可能小于对映体和相反的带电CD之间的分离选择性，但是通过反EOF设置提高的分离度使得可以通过相同的带电CD分离对映体。

著录项

  • 作者

    Wang, Fang.;

  • 作者单位

    North Carolina State University.;

  • 授予单位 North Carolina State University.;
  • 学科 Chemistry Analytical.
  • 学位 Ph.D.
  • 年度 1998
  • 页码 204 p.
  • 总页数 204
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 化学;
  • 关键词

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