Dynamic Light Scattering analyzes the interference pattern produced when laser light is scattered by passing through a sample solution. The fluctuations of the interference pattern correlates with the size of the particles, which allows the size distribution to be determined. In Z-potential mode the sample solution is also exposed to an electrical field, and the change in fluctuations when the field is ON/OFF is used to determine the surface charge of the particles, the so called zeta potential.
Malvern Zetasizer Ultra can measure Dynamic Light Scattering at forward, side , or back-scatter angles, or do a combined multi-angle measurement (MADLS). The particle size range is 1 nm – 10 um, though sample sedimentation can further limit the possibility to measure large/heavy particles. In addition to size distribution, MADLS can also be used to determine sample concentration. Zeta potential is determined using Phase Analysis Light Scattering (M3-PALS).