Charged molecules like proteins can be separated in an electrical field by size, charge and/or isoelectric point. Electrophoresis can be performed in a solid matrix or in a liquid, with native or denatured proteins, at analytical or preparative scale and in the presence of cationic, anionic or nonionic detergents. Detection of separated protein molecules can be by absorption, fluorescence, bound radioactivity or binding of specific antibodies.