The ζ potential is an important parameter to understand attractive and repulsive forces in particulate systems and is considered to be essential in many product sectors. Carina Santner, product specialist for particle characterization at Anton Paar, says the ζ-potential measurements are often a fundamental quality-control parameter in the formulation of cosmetics, paints, inks, syrups, or infusions because of their direct relation to product stability.
In cosmetics, the ζ potential can be determined for any product that contains particulate structures, such as liposomes. These hydrophobic particles increase the efficacy of skin care products by delivering ingredients into the deepest layer of skin. “Usually you aim for low ζ-potential values in order to increase the uptake of your liposomes and membrane interactions. The cell membrane is negatively charged; therefore, low values result in a better interaction between cell membrane and liposomes,” Santner says.
Santner says the dosing system feature of the Anton Paar Litesizer 500 is useful for achieving optimal ζ-potentials because it can measure the ζ potential in a range of different pH values, and pH is known to have a big influence on the ζ potential.
“Understanding the electrophoretic properties of a skin care product is a crucial factor in formulation design. It is necessary to select the right formulation of pH value, buffers, and emulsifier to maximize the ζ potential and hence predict the product stability,” Santner says.
“Using the dosing system, users can avoid adjusting the pH manually,” she notes. “Automating this process not only saves time and effort but, most importantly, also considerably reduces the possibility of human error in terms of better accuracy and reproducibility.”