What is surface zeta potential and how to measure it?

Surface zeta potential cell showing the mounting bracket for the sample plate

The Zetasizer Nano has an optional Surface Zeta Potential cuvette, which can be used to help gain an understanding of the charge at interfaces . The surface zeta potential cell is intended for the measurement of the zeta potential at the surface of a flat material in an aqueous environment.

The Zetasizer has been around for a few years, and the Zetasizer series now includes several models (90 degrees, backscattering, size and zeta, flowmode for chromatography detection, automated plate sampler).  One of the unique accessories for the zeta potential capable models is the surface zeta potential cell. It is listed on our cell and cuvette options.

What is the surface zeta potential and how can it be measured?

how the surface zeta potenial is obtainedIn aqueous systems, almost all wall surfaces will acquire some kind of charge. This charge can influence the mobility of tracer particles diffusing close to the wall. The electrophoretic mobility or Zeta potential is highly dependent on both the sample surface and the medium in which it is immersed. By measuring the zeta potential of tracer beads as a function of distance from the surface of investigation, the surface zeta potential can be obtained. The cuvette itself has part number ZEN1020 and the consumable PEEK sample holders can be reordered under part number ZEN4060. As a glue many household fasteners, like cyanoacrylate, should work well.

For tracer particles, often the negatively charged polystyrene beads in the Malvern transfer standard DTS1235 may be suitable. For positive charge, the dilute fabric softener Downy® can provide quite reasonable cationic particles. There is also the choice of carboxylated melamine particles such as MEL0665 and MEL1180 as an option.

Further zeta potential resources

Movie: Practical steps on how to make a measurement with the surface zeta potential cell

Previously

If you have any questions, please email me at ulf.nobbmann@malvern.com. Thanks!
While opinions expressed are generally those of the author, some parts may have been moderated by our editorial team.