Capillary isoelectric focusing: a routine method for protein analysis?

Although isoelectric focusing (IEF) in the slab gel format is a widely used technique in protein analysis, capillary isoelectric focusing (CIEF) is not yet a method used routinely, despite major advantages. This may be due to the fact that several methods for performing IEF in the capillary can be found in the literature, differing in the manner of mobilizing the focused protein zones for detection. We therefore discuss and compare the three most widely used CIEF techniques - using chemical, pressure, or electroosmotic flow (EOF) mobilization - with respect to linearity of the calibration curve, resolution, and reproducibility.