Separation Power in Electrophoresis

Isoelectric focusing (IEF) is a steady-state zonal electrophoretic technique. Using IEF, proteins can be separated according to differences in their isoelectric points. The principles of IEF are described in Sections 8.10 and 8.11. 

Many 2D planar structures have been used to implement deflection (continuous flow) electrophoresis. The primary requirement is that flow and electrophoresis be carried out simultaneously and uniformly. Hanging paper curtains soaked with electrolyte and fed a stream of electrolyte from above served admirably for this purpose when the technique was initiated in the 1950s. In recent years thin flow channels enclosed between flat plates have become important. The process is complicated by parabolic flow, which distorts and effectively broadens the electrophoretic zones. More detail is available in the cited references on electrophoresis [3-5]. 

Two-dimensional discrete (as opposed to continuous) electrophoresis has become a premier analytical tool for separating complex protein mixtures. Since this technique employs IEF, further discussion will be postponed to Section 8.10. 

Here we establish the number of theoretical plates and separable zones achievable in ideal zone electrophoresis by following the approach in ref. [1]. This analysis aids in system evaluation, comparison, and optimization. 

The electrostatic force exerted on a mole of charged particles by an electrical field of strength E is 

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