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. This kit can help gain an understanding of the charge at interfaces . Thus, the surface zetapotential cell measures the zeta potential at the surface of a planar flat material in an aqueous environment.

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

What is the surface zeta and how can we measure it?

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.

We can measure the zeta potential of tracer beads as a function of distance from the surfaceplane of investigation. This then extrapolates to the surface zetapotential. The cuvette itself has part number ZEN1020 . Likewise, 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, however, 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 surfacezeta potential cell

Previously

If you have any questions, please email me at ulf.nobbmann@malvern.com. Thanks!
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