Isoelectric focussing additives

Subsequently four different CE modes are described in the sections Capillary Zone Electrophoresis, Capillary Gel Electrophoresis, Capillary Isoelectric Focussing, and Micellar Electrokinetic Chromatography (MEKC), respectively. The fundamental principles of the specific separation modes are briefly explained, using appropriate equations where required. In Table 3 all equations are listed. In addition, the influence of both instrumental parameters and electrolytic solution parameters on the optimization of separations is described. 

Proteins often precipitate during isoelectric focussing because (1) they are concentrated into a sharp band and (2) they do not exhibit any net charge at their pi and can thus undergo extensive hydrophobic interaction. To improve solubility, a number of additives can be used. The denaturing agent urea may be used at concentrations of up to 6M. Non-ionic and zwitterionic surfactants are also commonly used. 

Elemental analysis (C,H and N), determination of gadolinium by Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma (ICP) have been used routinely. Additionally, gel permeation chromatography, gel and capillary electrophoresis as well as isoelectric focussing are useful tools for the characterization of Gadomer. 

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