Electrophoresis

Electrophoresis

Colloidal particles have a large surface area, which enables them to adsorb either positively or negatively charged ions from the surrounding medium. As a result, these particles acquire a net electric charge and become charged colloids. When a colloidal solution is subjected to an electric field, its charged particles drift toward the oppositely charged electrode. This phenomenon is known as electrophoresis.

The movement direction is determined by whether the colloidal particles carry a positive or negative charge.

• If the colloidal particles are positively charged, they move towards the cathode (negative electrode). This type of movement is termed cataphoresis. An example of this is a ferric hydroxide (Fe(OH)₃) sol, which contains positively charged colloidal particles.
• If the colloidal particles are negatively charged, they move towards the anode (positive electrode). This process is known as anaphoresis. A common example is blood, which behaves as a negatively charged colloidal system and undergoes anaphoresis under an electric field.

Types of Electrophoresis

Based on the nature of the charge on colloidal particles, electrophoresis can be classified into:

• Cataphoresis: Refers to the migration of particles with a positive charge in the direction of the cathode.
• Anaphoresis: Refers to the migration of negatively charged particles toward the anode.

Applications

• Used in the purification and separation of colloids.
• Essential in biological studies like DNA and protein analysis.
• Employed in laboratories for diagnostic and research purposes.