The Nicomp 380/ZLS is designed to measure the electrophoretic mobility and zeta potential of charged particles in liquid suspension. The main reason to measure zeta potential is to predict colloidal stability. The interactions between particles play an important role in colloidal stability. The use of zeta potential measurements to predict stability is an attempt to quantify these interactions. The zeta potential is a measure of the repulsive forces between particles. And since most aqueous colloidal systems are stabilized by electrostatic repulsion, the larger the repulsive forces between particles, the less likely they will be to come close together and form an aggregate. Thus the more stable a colloid will be. The Nicomp 380/ZLS combines the techniques of Dynamic Light Scattering (DLS) and Electrophoretic Light Scattering (ELS) to measure both sub-micron particle size distributions and zeta potentials in one compact instrument.