FACTORS AFFECTING ELECTROPHORETIC MOBILITY

The Sample

Charge/mass ratio ofthe sample dictates its electrophoretic mobility. The mass consists of not only the size (molecular weight) but also the shape of the molecule.

(i) Charge. The higher the charge, greater is the electrophoretic mobility. The charge, however, is dependent on pH of the medium.

(ii) Size. The bigger the molecule, greater are the frictional and electrostatic forces exerted upon it by the medium of suspension. Consequently, larger particles have a smaller electrophoretic mobility compared to the smaller particles.

(iii) Shape. Rounded contours elicit lesser frictional and electrostatic retardation compared to sharp contours. As an example consider the case of globular and fibrous proteins. Given the same size (molecular'weight) the globular protein will migrate faster than the fibrous protein.

The Electric Field

The Medium

The Buffer

 

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