Electrophoresis, a process used in biology and chemistry to separate and identify particles, such as ions or colloidal particles, found in liquid mixtures. Electrophoresis is used mostly to separate and identify proteins, which are colloidal particles. Electrophoresis consists basically of passing an electric current through a mixture, causing the various particles in the mixture to migrate at different velocities to the anode or cathode, depending on such factors as the charge of the particle, pH (degree of acidity or alkalinity) of the liquid, and voltage of the current.

The most widely used method of electro-phoresis is called zone electrophoresis. A small amount of the mixture to be analyzed is applied in a streak across a paper-thin strip of celluloid acetate saturated with a solution whose properties, such as pH, are known. When the current is applied, each of the different kinds of particles migrates across the celluloid strip, leaving a distinctive pattern on the strip.