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electrophoresis unit. All electrophoresis is carried out in an appropriate buffer, which is

essential to maintain a constant state of ionisation of the molecules being separated.

Any variation in pH would alter the overall charge and hence the mobilities (rate of

migration in the applied field) of the molecules being separated.

Fig. 10.1Photograph showing samples being loaded into the wells of an SDS–PAGE minigel. Six wells that

have been loaded can be identified by the blue dye (bromophenol blue) that is incorporated into the loading buffer.

Cover

Gel

Compartment of buffer reservoir

Electrode

• ve

Electrode

+ ve

Cooling plate

Wick

Fig. 10.2A typical horizontal apparatus, such as that used for immunoelectrophoresis, isoelectric focussing

and the electrophoresis of DNA and RNA in agarose gels.

400 Electrophoretic techniques