Continuous preparative gel electrophoresis.

Electrophoresis is widely used as a separative technique, particularly in protein chemistry. In some respects gelatinous media have an advantage over others as support media for electrophoresis, perhaps most obviously when a gel matrix of molecular dimensions is employed, allowing the simultaneous use of two properties for separation of the particles of interest-size and surface charge density. Several devices have been described for preparative gel electrophoresis showing that there is widespread interest in the possibility of applying this powerful analytical technique on a larger scale (I-G). The idea of continuous operation is always attractive for preparative "'ork. Continuous electrophoresis was introduced over 20 yr ago, but it has hitherto been confined to media readily permeable to water (7) or to conditions of free solution (8-14) where subtle and fascinating approaches have been used by many workers to prevent convective mixing. This paper describes an apparatus for continuous electrophoresis in a gel medium, not freely permeable, commencing with an account of the principle upon which such a device must depend, and also indicates how this relates to other techniques in a general classification of electrophoretic processes. Consider a strip or slab of gel which is transported continuously in a direction parallel to one of its faces. (By "face" we mean to include the nalTOW face or edge of a thin rectangular slab.) If a sample solution is applied continuously to this face and if an electric field is applied continuously in a direction at a right angle to the direction of transport,