Australian Centre for Research on Separation Science (ACROSS), School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania, Australia, 7001.
Australian Centre for Research on Separation Science (ACROSS), School of Natural Sciences-Chemistry, University of Tasmania, Hobart, Tasmania, Australia, 7001.
Talanta. 2020 Feb 1;208:120401. doi: 10.1016/j.talanta.2019.120401. Epub 2019 Sep 27.
Fundamental studies on the separation of cationic and anionic analytes in open-tubular admicellar electrochromatography (OT-AMEC) using cetyltrimethylammonium bromide (CTAB) and fused silica capillaries are presented. OT-AMEC was compared with open-tubular admicellar liquid chromatography (OT-AMLC) by running the two methods using the same mobile phases. The mobile phases were buffered at pH ≥ 6 and contained a low concentration (above the critical surface aggregation concentration and below the critical micelle concentration) of CTAB. The stationary pseudophase of CTAB admicelles were formed at the solid surface and liquid interface inside the capillary by simply conditioning the capillary with the mobile phase. Separations were performed in a 30 cm (21.5 cm to UV detector) long and 50 μm inner diameter capillary, using low pressure (50 mbar) in OT-AMLC and high voltage (15 kV at negative polarity) in OT-AMEC. The appropriate equations for the experimental estimation of retention factor (k) values of analytes were discussed. For anionic analytes, k in OT-AMEC were carefully determined by considering the observed interaction between CTAB monomers and tested analytes. The calculated k for each analyte was found similar in OT-AMLC and OT-AMEC, although the mechanism of retention was not entirely different due to the contribution of electrophoresis in OT-AMEC. Studies on the addition of a typical (i.e., acetonitrile) and atypical modifier (i.e., nonyl-β-glucoside) into the mobile phase, and sample focusing with >10x improvement in peak height under isocratic conditions were also conducted.
本文主要研究了在使用溴化十六烷基三甲铵（CTAB）和熔融石英毛细管的开管吸附胶束电动色谱（OT-AMEC）中分离阳离子和阴离子分析物的基础问题。通过使用相同的流动相运行两种方法，将 OT-AMEC 与开管吸附胶束液相色谱（OT-AMLC）进行了比较。流动相在 pH≥6 时缓冲，并含有低浓度（高于临界表面聚集浓度且低于临界胶束浓度）的 CTAB。通过用流动相简单地处理毛细管，在毛细管的固体表面和液体界面内形成 CTAB 胶束的固定伪相。在 30cm（21.5cm 到 UV 检测器）长、50μm 内径的毛细管中进行分离，在 OT-AMLC 中使用低压（50mbar），在 OT-AMEC 中使用高压（15kV 负极性）。讨论了用于实验估计分析物保留因子（k）值的适当方程。对于阴离子分析物，通过考虑 CTAB 单体和测试分析物之间的观察到的相互作用，仔细确定了 OT-AMEC 中的 k。对于每种分析物，在 OT-AMLC 和 OT-AMEC 中计算得到的 k 相似，尽管由于电泳在 OT-AMEC 中的贡献，保留机制不完全相同。还研究了在流动相中添加典型（即乙腈）和非典型（即壬基-β-葡萄糖苷）改性剂，以及在等度条件下通过 >10 倍的峰高浓缩样品。
