Department of Chemistry and Centre for Research on Biomolecular Interactions, York University, Toronto, Ontario M3J 1P3, Canada.
Anal Chem. 2012 Jan 3;84(1):149-54. doi: 10.1021/ac203129h. Epub 2011 Dec 12.
Pressure-driven sample injection in capillary electrophoresis results in asymmetric peaks due to difference in shapes between the front and the back boundaries of the sample plug. Uneven velocity profile of fluid flow across the capillary gives the front boundary a parabolic shape. The back side, on the other hand, has a flat interface with the electrophoresis run buffer. Here, we propose a simple means of correcting this asymmetry by pressure-driven "propagation" of the injected plug, with the parabolic sample-buffer interface established at the back. We prove experimentally that such a propagation procedure corrects peak asymmetry to the level comparable to injection through electroosmosis. Importantly, the propagation-based correction procedure also solves a problem of transferring the sample into the efficiently cooled zone of the capillary for capillary electrophoresis (CE) instruments with active cooling. The suggested peak correction procedure will find applications in all CE methods that rely on peak shape analysis, e.g., nonequilibrium capillary electrophoresis of equilibrium mixtures.
压力驱动的毛细管电泳中的样品注入会导致不对称峰，这是由于样品塞的前后边界形状不同所致。流体在毛细管中流动的速度分布不均匀，使得前边界呈抛物线形状。另一方面，后边界与电泳运行缓冲液具有平坦的界面。在这里，我们提出了一种通过压力驱动的“传播”来校正这种不对称性的简单方法，在后端建立了抛物线的样品-缓冲界面。我们通过实验证明，这种传播过程可以将峰不对称性校正到与电渗流注入相当的水平。重要的是，基于传播的校正过程还解决了将样品转移到具有主动冷却的毛细管电泳（CE）仪器的高效冷却区的问题。所提出的峰校正程序将应用于所有依赖于峰形分析的 CE 方法，例如平衡混合物的非平衡毛细管电泳。
