Emulsions are two phase systems composed of a dispersed phase (the droplets or particles) and a continuous phase (liquid diluent such as water). The size of the droplets in the dispersed phase is critically important. There are several ways of measuring the size of emulsion droplets, including dynamic light scattering (DLS), zeta potential, laser diffraction, and single particle optical sizing (SPOS) in the laboratory. This talk will discuss their advantages and disadvantages of each.

The only official test for testing emulsion droplet size is USP <729>. The talk will review Methods I and II for measuring the mean size and tail of the droplet distribution using dynamic light scattering or laser diffraction and single particle optical sizing. This same approach can be applied to other emulsions beyond lipids. An example of a CBD oil emulsion will demonstrate how the USP 729 method can be expanded beyond lipid emulsions.

While almost all emulsion droplet size analysis is currently performed in the laboratory, online analysis by DLS is also an option. How to perform in-process measurements and example results for several pharmaceutical emulsions will be covered including Intralipid, Propofol, and Lipomed.

Mark Bumiller
Mark is Technology Manager for the instrumentation group (formerly Particle Sizing Systems) at Entegris, Inc. Mark has worked in the field of particle size analysis for over thirty five years. He has served as a member of the expert committee for USP 788, the executive committee of the International Fine Particle Research Institute, and the executive committee of Particle Technology Forum of the American Institute of Chemical Engineers. Mark is an active member of ISO Technical Committee 24, SC4 helping to write standards for particle size and zeta potential analysis.