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Updated: Sep 27, 2026

Highly Sensitive and Quantitative Detection of Proteins and Their Isoforms by Capillary Isoelectric Focusing Method
Published on: September 19, 2018
On-line hyphenation of capillary isoelectric focusing and capillary gel electrophoresis by a dialysis interface
Chun Yang1, Hechun Liu, Qing Yang
1National Chromatographic R. & A. Center, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116011, China.
Abstract:
An on-line two-dimensional (2D) capillary electrophoresis (CE) system consisting of capillary isoelectric focusing (CIEF) and capillary gel electrophoresis (CGE) was introduced. To validate this 2D system, a dialysis interface was developed by mounting a hollow fiber on a methacrylate resin plate to hyphenate the two CE modes. The two dimensions of capillary shared a cathode fixated into a reservoir in the methacrylate plate; thus, with three electrodes and only one high-voltage source, a 2D CE framework was successfully established. A practical 2D CIEF-CGE experiment was carried out to deal with a target protein, hemoglobin (Hb). After the Hb variants with different isoelectric points (pIs) were focused in various bands in the first-dimension capillary, they were chemically mobilized one after another and fed to the second-dimension capillary for further separation in polyacrylamide gel. During this procedure, a single CIEF band was separated into several peaks due to different molecular weights. The resulting electrophoregram is quite different from that of either CIEF or CGE; therefore, more information about the studied Hb sample can be obtained.
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