Factors governing emulsion droplet and solid particle size measurements performed using the focused beam reflectance technique

The focused beam reflectance (FBRM) method is a relatively new method, developed to perform particle size measurements in the range 0.8–1000 μm. The particle size determined is given in terms of a chord length. The relationship between chord length and particle size obtained using other methods (image analysis and Malvern Mastersizer) has been investigated. The advantage of the FBRM method is the ability to perform in-situ particle size analysis in real time, without the need for sampling or dilution. In this work, we study the effects of various experimental factors (e.g. agitation rate and particle concentration) on FBRM measurements, and compare the size distributions with those obtained by other sizing methods. FBRM has also been used for studying the formation of (oil-in-water) emulsion droplets (with a droplet size >100 μm) with time under shear, where both sampling and dilution may affect the droplet size distribution.