Electrophoretic light scattering (ELS) investigates the behavior of samples under the influence of an applied electric field. Two terms often used in connection with ELS experiments are electroosmosis and electrophoresis. While these terms are
related, they refer to slightly different phenomena.
Electroosmosis is the movement of liquid relative to a stationary charged surface under the influence of an applied electric field.
Electrophoresis is the movement of charged particles under the influence of an applied electric field (see figure below).
The main interest in ELS studies is the characterization of particles. Therefore, modern ELS instrumentation attempts to minimize electro-osmotic effects and measure only electrophoresis.