Density gradient electrophoresis isoelectric focusing

In considering the applicability of preparative classical electrophoretic methods to chiral separations, it should be noted that practitioners in the art of classical electrophoresis have been particularly inventive in designing novel separation strategies. For instance, pH, ionic strength and density gradients have all been used. Isoelectric focusing and isotachophoresis are well-established separation modes in classical electrophoresis and are also being implemented in CE separations [7, 8]. These trends are also reflected in the preparative electrophoretic approaches discussed here. 

Two variations of the basic technique are isoelectric focusing and immuno-electrophoresis. The former offers improved resolution and sharper bands in the separation of weak acids, weak bases and ampholytes through the use of pH and density gradients superimposed along the potential gradient. The latter employs specific antigen-antibody interactions (Chapter 10) to visualize the separated components of serum samples. 

Isoelectric focusing and electrofocusing are names that have been accepted, and in current use, since 1967. Before that time the technique was called isoelectric separation, isoelectric fractionation, isoelectric condensation, isoelectric analysis and focusing electrophoresis, as well as stationary electrolysis. Terms such as density gradient electrofocusing or gel electrofocusing indicate the medium in which the experiments are carried out. 

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