A technique used to separate mixtures of solute molecules or colloidal particles in solution by placing them in an electric field. Molecules with a net positive charge (cations) move towards the cathode (negative electrode) and those with a net negative charge (anions) move towards the anode (positive electrode). The speed of movement of the molecules depends on their net charge, which in turn depends on the pH of the medium. The size of the molecule and the strength of the voltage applied also affect the speed of movement. Often the solvent is a gel of, for example, starch, agar, or polyacrylamide. These prevent the passage of small molecules, which become caught within the molecules of the gel (see gel filtration), so enabling clearer separation of the larger molecules. Electrophoresis is often used to separate the components of protein mixtures and may be used in conjunction with paper chromatography. See also immunoelectrophoresis. |
