Electromigration:

The simplest example of separation by migration under electric field is controlled potential electrodeposition.  This technique is quite effectual for the separation of certain metal ions in the presence of other metal ions. But in the normal categorization of separation methods, it is not given its due recognition. Therefore, the methods such as electrophoresis and electrochromatography in that an electric field is utilized to generate or affect the associative motion of charged species in solution, have gained more prominence. The two frontline techniques included under this head are electrophoresis and electrochromatography.

In electrophoresis, only the electric field causes the motion while in electrochromatography, the movement is caused by the resultant of an electric and a gravitational (or other non-electrical) forces. Electrophoretic separations are performed in two different ways. One is known as slab electrophoresis and the other capillary electrophoresis.

In slab electrophoresis, a filter paper, porous glass or a gel cast within the form of a bed could be used. Samples are introduced as spots or band and a dc potential is applied across the slab for a fixed period. The separated species are visualized by staining in a way similar to TLC.