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首页> 外文期刊>Electrophoresis: The Official Journal of the International Electrophoresis Society >Non-uniform surface charge distributions in CE: Theoretical and experimental approach based on Taylor dispersion.
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Non-uniform surface charge distributions in CE: Theoretical and experimental approach based on Taylor dispersion.

机译：CE中的不均匀表面电荷分布：基于泰勒色散的理论和实验方法。

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The control of the EOF direction and magnitude remains one of the more challenging issues for the optimization of separations in CE. In this work, we investigated the possibility to use non-uniform surface charge distribution for the modulation of the EOF in CE. Non-uniform zeta potentials were obtained by modifying a section of the capillary surface using adsorption of polyelectrolytes. Three different methods were studied: (i) partial polycation coating on a fused silica capillary, (ii) partial polycation (or polyanion) coating on polyelectrolyte multilayers, and (iii) partial polycation coating on a capillary previously modified with poly(ethylene oxide). The magnitude and the direction of the EOF as a function of the coated capillary length were first studied. The stability of the EOF and the separation performances were also considered taking two dialanine diastereoisomers as model compounds. In partially coated capillaries, the average solvent flow is the sum of two contributions: a non-dispersive electroosmotic contribution related to the capillary surface charge, and a dispersive hydrodynamic contribution that depends on the difference of surface charge between the coated and the non-coated capillary zones. To get a better insight into the influence of the hydrodynamic contribution to the total peak dispersion, the peak variances corresponding to the Taylor dispersion, the injection plug, and the axial diffusion were calculated. This work demonstrates that peak dispersion in a capillary partially coated by the inlet end is different from that obtained when the coating is performed by the outlet end. Experimentally, the combination of a partially coated capillary with a large volume sample stacking preconcentration step can be used for injecting up to 95% of the capillary volume. This approach leads to a preconcentration factor of 60 compared with CZE with classical injection.
机译：EOF方向和大小的控制仍然是优化CE分离的更具挑战性的问题之一。在这项工作中，我们研究了使用非均匀表面电荷分布对CE中EOF进行调制的可能性。通过使用聚电解质的吸附修饰毛细管表面的一部分，可获得非均匀的ζ电势。研究了三种不同的方法：（i）在熔融石英毛细管上的部分聚阳离子涂层，（ii）在聚电解质多层上的部分聚阳离子（或聚阴离子）涂层，以及（iii）在事先用聚环氧乙烷改性的毛细管上的部分聚阳离子涂层。首先研究了EOF的大小和方向与涂层毛细管长度的关系。还以两种二烷胺非对映异构体为模型化合物考虑了EOF的稳定性和分离性能。在部分涂层的毛细管中，平均溶剂流量是两个贡献的总和：与毛细管表面电荷相关的非分散电渗作用，以及取决于涂层和未涂层​​之间的表面电荷之差的分散流体动力作用毛细血管区。为了更好地了解流体动力学对总峰弥散的影响，计算了与泰勒弥散，注入塞和轴向扩散相对应的峰方差。该工作表明，在由入口端部分涂覆的毛细管中的峰分散与当由出口端进行涂覆时获得的峰分散不同。实验上，部分涂覆的毛细管与大体积样品堆积预浓缩步骤的组合可用于注入高达95％的毛细管体积。与传统进样的CZE相比，这种方法的预浓缩系数为60。

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