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Electrophoresis can be divided into two main techniques: free electrophoresis or electrophoresis without stabilizing media and zone electrophoresis or electrophoresis in stabilizing media.

Free electrophoresis

Free electrophoresis has two main techniques: microelectrophoresis and moving boundary electrophoresis. Both the techniques have now become obsolete and are at best of historical significance.

Microelectrophoresis

This electrophoretic technique involves the observation of motion o f small particles in an electric field with a microscope. The suspension is contained in a closed system composed of a thin walled section for optical observations and of suitable electrode compartments. In principle any microscope with a graduated fine focusing adjustment and an ocular micrometer may be used in conjunction with a flat electrophoretic cell. The ocular micrometer serves for the measurement of the electrophoretic mobility of the microscopic particles in conjunction with a stopwatch. In modern days this technique is applied only for measuring the zeta potentials of cell such as rbc, neutrophils, bacteria etc.

Moving boundary electrophoresis

This is the prototype of all modern methods of electrophoresis and was first developed by A. Tiselius of Sweden in the 1930s. In moving boundary electrophoresis a buffered solution of macromolecules is placed under a layer of pure buffer solution in a U-shaped observation cell. The whole cell may then be immersed in a constant temperature bath insulated from vibrations. The power is switched on generating an electric field between the electrodes. Normally in a complex sample containing many macromolecules, there will be species, which will bear a net negative charge and therefore move towards the anode while at the same time the macromolecules bearing a net positive charge will move towards cathode. This situation of movements in mutually opposite directions will not be good for a satisfactory resolution. The pH of the buffer is, therefore, so chosen that all the macromolecules bear a net negative charge. The movement of macromolecules consequent to generation of electric field between the electrodes will then be towards the anode. As they do so, they migrate from the macromolecule solution to the pure buffer or into the zone of macromolecule free buffer and from a boundary or front. As a result of this there is sharp change in the refractive index of the solution at this boundary. The refractive index changes along the electrophoretic cell, when measured by appropriate optical devices, yield electrophoretic patterns that show the direction and relative rate of migration of the major molecules in the sample.

For many years moving boundary method was very popular for quantitative analysis of complex mixtures of macromolecules, especially proteins those in blood plasma. In recent years, however, it has been superceded by techniques collectively known as zone electrophoresis.