Resolution of proteins by isoelectric focusing is due to the pH gradient, the thickness of the gel, the time of electrophoresis, the applied voltage, and the diffusion of protein into the gel. Resolution is the separation of protein bands relative to their band widths. It is denoted by the differences in IpH between two distinguishable bands. A narrow pH range means more distance between IpH's and better resolution. High electrical fields produce shorter run times, but large amounts of heat can cause the gels to burn.
Resolution decreases with increasing temperature due to increased diffusion.
Resolution can also decrease with excessive time, due to gradient drift. Gel thicknesses are commonly 0.8 to 1.0 mm thick. In turn, this gives better protein resolution, shorter run times, easier staining, and an easier removal of proteins. The sample should usually be in deionized water that has been thoroughly dialyzed against HPLC water. Salts and high molar concentrations of buffers can counteract the protein's movement in an IEF pH gradient.