Zeta potential is an electrical charge that is located at the interface of solid particles in a liquid. This charge is of great importance for certain reaction mechanisms with other substances.

It is not possible to measure this charge directly, but the zeta potential can be calculated using the so-called streaming potential method.

Since the particles of a liquid have a positive or negative charge, around these particles there are ions and/or colloidal particles with charges that are exactly opposite to the charge of the particles themselves. If this counter-charge of the particles is canceled by transverse forces, a measurable voltage potential arises. The ratio of this potential to the zeta potential is given in the following formula:

In SZP04 the dielectric constant and the viscosity of water are assumed. With 4p and a device constant that is determined empirically, these result in a constant factor of 7.

The flow potential U, the conductivity S and the force P (that is the pressure difference in the measuring cell) are determined during the measurement.