Herr AE, Molho JI, Santiago JG, Mungal MG, Kenny TW, Garguilo MG
Stanford University, California 94305-4021, USA.
Anal Chem. 2000 Mar 1;72(5):1053-7. doi: 10.1021/ac990489i.
The present work is an analytical and experimental study of electroosmotic flow (EOF) in cylindrical capillaries with nonuniform wall surface charge (zeta-potential) distributions. In particular, this study investigates perturbations of electroosmotic flow in open capillaries that are due to induced pressure gradients resulting from axial variations in the wall zeta-potential. The experimental inquiry focuses on electroosmotic flow under a uniform applied field in capillaries with an EOF-suppressing polymer adsorbed onto various fractions of the total capillary length. This fractional EOF suppression was achieved by coupling capillaries with substantially different zeta-potentials. The resulting flow fields were imaged with a nonintrusive, caged-fluorescence imaging technique. Simple analytical models for the velocity field and rate of sample dispersion in capillaries with axial zeta-potential variations are presented. The resulting induced pressure gradients and the associated band-broadening effects are of particular importance to the performance of chemical and biochemical analysis systems such as capillary electrokinetic chromatography and capillary zone electrophoresis.
本工作是对具有非均匀壁面电荷（zeta 电位）分布的圆柱形毛细管中电渗流（EOF）进行的分析和实验研究。具体而言，本研究调查了开放毛细管中电渗流的扰动，这些扰动是由壁面 zeta 电位的轴向变化所导致的感应压力梯度引起的。实验探究聚焦于在均匀外加电场下，毛细管中吸附有抑制电渗流聚合物的电渗流情况，该聚合物吸附在毛细管总长度的不同部分。这种部分抑制电渗流是通过耦合具有显著不同 zeta 电位的毛细管来实现的。使用非侵入式笼形荧光成像技术对所得流场进行成像。给出了具有轴向 zeta 电位变化的毛细管中速度场和样品分散速率的简单分析模型。由此产生的感应压力梯度和相关的谱带展宽效应对于化学和生化分析系统（如毛细管电动色谱和毛细管区带电泳）的性能尤为重要。
