cataphoresis

Cataphoresis is a term used in electrostatics and electrophoresis to describe the migration of charged particles in an electric field toward the cathode, the negative electrode. It is one component of electrophoretic transport, with anaphoresis describing the analogous movement of negatively charged species toward the anode.

The movement results from the electrical force acting on charged particles within a medium. Observed migration depends on particle charge, size, and shape, as well as the properties of the surrounding medium, such as its ionic strength and pH. The applied electric field strength and duration also influence how far and how fast particles travel. In practice, electroosmotic flow—the bulk movement of the fluid itself under an electric field—can modify the net motion, either enhancing or opposing cataphoresis.

Applications and context: Cataphoresis concepts underpin many electrophoretic techniques used in chemistry and biology, including gel and capillary electrophoresis, where charged biomolecules migrate under controlled electric fields to effect separation. The term is more often encountered in historical or specialized discussions of electrophoretic transport, rather than in everyday laboratory practice, where emphasis is placed on electrophoretic mobility and separation behavior rather than directional nomenclature.

Etymology: from Greek kata, meaning “down,” and phoresis, meaning “carrying.”