Lifetime of the Anton Paar Omega Cuvette for Zeta-Potential Measurements

Zeta potential is a key indicator of colloidal stability. When a colloid has high zeta potential (positive or negative), the colloidal particles tend to repel each other, so the chance of agglomeration is low. A low zeta potential, on the other hand, may lead to aggregation due to the low repelling forces between the particles. Thus, zeta potential is an important factor for the preparation or destruction of colloidal dispersions across diverse industries, such as biomedical technology, polymers, paper, paints and coatings, and pharmaceuticals.

Zeta potential can be obtained through electrophoretic light scattering (ELS), in which the electrophoretic mobility is measured, and then used to calculate the zeta potential. In ELS, a laser beam irradiates the dispersion and is then scattered by the particles in the dispersion. The frequency of the incident light is shifted proportionally to the particles' movement, so the electrophoretic mobility can be obtained from the shift (Doppler shift) of the scattered light by using the Smoluchowski/Hückel approximation. ELS measurements are easy to automate and highly reproducible, even with complex samples.

Anton Paar's Omega cuvettes for zeta-potential are made of polycarbonate, which has excellent chemical stability, abrasion resistance and scratch resistance. A unique feature of Anton Paar's Omega cuvette is the shape of the capillary tube, which resembles an inverted omega. Compared to the more standard U-shaped tube, the omega-shaped tube avoids the build up of a gradient in the strength of the electric field in the part of the capillary where the particle speed is being measured. Thus, measurements with Anton Paar's Omega cuvettes are independent of measurement position, and are highly stable and reproducible.

Anton Paar's Omega cuvette includes two electrodes that are coated with a 2 µm gold layer to induce an electric field. The aim of this technical note is to test the long-term durability of the Anton Paar Omega cuvette. 

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