At nano engineering company Sol-Gel Technologies (Bet Shemesh, Israel), Malvern’s Zetasizer Nano particle characterization system is proving to be an essential tool in the production of a unique product for encapsulating UV filters. The Zetasizer Nano is used to measure the particle size distribution of the company’s UV Pearls product, both for process control and as part of the QC specifications of the final materials. The system was selected because, of all the instruments evaluated, it gave the most reproducible results across the narrow size ranges required, from 300 nm to 2 microns.
Dr Ofer Toledano, Sol-Gel Technologies’ R&D Manager, explains the importance of controlling particle size: “UV filters are widely used in sunscreens, but can themselves cause skin damage. Our process encapsulates the UV-filter in a glass bead, retaining its UV protective properties, but preventing direct contact with the skin. If, on the one hand, the particle size is too large, the sun protection factor is reduced. If, on the other hand, it is too small, skin penetration may occur.”
Production of the UV Pearls entails an emulsification process, followed by encapsulation and dispersion. The particle size distribution of the dispersion must conform to strict specifications within a narrow range. Particles larger than 2 microns in diameter may result in non-uniform coverage of the skin since gaps between the particles will allow UV penetration.
Sol-Gel’s UV Pearls are marketed by Merck KgaA and is used in a variety of sunscreen products around the world.
Malvern’s Zetasizer Nano series simplifies the measurement of particle size, stability characterization using zeta potential, and molecular weight, for a wide range of dispersions, emulsions and molecules in solution. It is the method of choice for nano-particle applications from routine colloid size measurements to the investigation of particulates at the leading edge of materials research. Patented technologies ensure optimum performance for particle size measurement over the range 0.6 to 6000 nm, molecular weight measurement from 1 x 103to 2 x 107Daltons and the zeta potential of particles from 5 nm to 10 µm. www.malvern.com