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Toward more practical electrochromatography.

机译：走向更实用的电色谱。

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摘要

Capillary electrochromatography (CEC) is a rapidly developing separation technique which promises high efficiency separations in reasonable periods of time with low solvent consumption. In spite of these advantages, electrochromatography is not commonly used as it is not a practical technique for routine analysis. Our work has focused on making CEC more practical through instrument design and solvent selection.; CEC is a chromatographic technique, thus the general elution problem may be seen when complex samples are analyzed. When the general elution problem occurs, it is impossible to adequately separate all of the solutes in a reasonable period of time using one mobile phase composition. We utilized a flow injection interface for the generation of solvent gradients in CEC. This allows for the resolution of the early eluting solutes while forcing the more strongly retained solutes off the column in a reasonable period of time. This system was shown to reproducibly generate solvent gradients with no significant pressure driven flow.; Next, two power supplies were used to increase the total electrical potential across the capillary. One power supply, operating in positive polarity mode was used to apply potential to the inlet vial. A second power supply, operating in negative polarity mode was used to apply the potential to the outlet vial. The two power supplies were then grounded at separate external ground screws. Experiments proved that the electrical potential was additive across the capillary. Additionally, the noise decreased as neither end of the capillary was ever more than half the total potential from ground. Very high efficiency separations were performed on a long capillary and very fast separations were performed on a traditional length capillary.; Finally, different solvent systems were investigated. First, CO 2/Methanol mixed mobile phases were tested. Unfortunately, the electroosmotic flow (EOF) generated was too slow to be of use in an analytical separation. In contrast, higher viscosity solvents than those traditionally used in pressurized separations were studied. It was found that propanol is a much stronger solvent than methanol, however, the EOF is relatively slow. Ternary mobile phases, where the organic solvent contained equal portions of acetonitrile and propanol, mixed with varying concentrations of water were found to provide the ideal balance of solvent strength and electroosmotic mobility.
机译：毛细管电色谱（CEC）是一项快速发展的分离技术，它有望在合理的时间内以低溶剂消耗实现高效分离。尽管有这些优点，电色谱并不常用，因为它不是常规分析的实用技术。我们的工作重点是通过仪器设计和溶剂选择使CEC更加实用。 CEC是一种色谱技术，因此在分析复杂样品时可能会遇到一般的洗脱问题。当出现一般的洗脱问题时，使用一种流动相组合物不可能在合理的时间内充分分离所有溶质。我们利用流动注射界面在CEC中生成溶剂梯度。这样可以解析早期洗脱的溶质，同时在合理的时间段内将保留更强的溶质从色谱柱中压出。已显示该系统可重现地生成溶剂梯度，而没有明显的压力驱动流。接下来，使用两个电源来增加毛细管上的总电势。使用一个在正极性模式下运行的电源向进样瓶施加电势。使用以负极性模式操作的第二电源将电势施加到出口小瓶。然后将两个电源通过单独的外部接地螺钉接地。实验证明，电势可在整个毛细管上相加。另外，由于毛细管的两端都没有超过接地总电位的一半，因此噪声降低了。在长毛细管上进行非常高效的分离，在传统长度毛细管上进行非常快速的分离。最后，研究了不同的溶剂体系。首先，测试了CO 2 /甲醇混合流动相。不幸的是，产生的电渗流（EOF）太慢，无法用于分析分离。相反，研究了比常规加压分离中使用的溶剂高粘度的溶剂。发现丙醇是比甲醇强得多的溶剂，但是，EOF相对较慢。发现三元流动相（其中有机溶剂包含等份的乙腈和丙醇）与不同浓度的水混合可提供溶剂强度和电渗迁移率的理想平衡。

著录项

  • 作者

    Rimmer, Catherine Ann.;

  • 作者单位

    The Florida State University.;

  • 授予单位 The Florida State University.;
  • 学科 Chemistry Analytical.
  • 学位 Ph.D.
  • 年度 2001
  • 页码 159 p.
  • 总页数 159
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 化学;
  • 关键词

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