PRINCIPLES OF ULTRASONIC DROPLET SIZE DETERMINATION IN EMULSIONS

Instruments based on ultrasonic spectrometry are becoming increasingly popular for determining the droplet size distribution of emulsions. T hey have major advantages over alternative technologies because they a re capable of analyzing emulsions which are concentrated and optically opaque, without disturbing the sample. This article reviews the physi cal principles of ultrasonic particle sizing, the experimental methods commonly used to make ultrasonic measurements, and the mathematical e quations used to convert ultrasonic measurements to droplet size distr ibutions. Ultrasonic spectrometry is compared to other particle-sizing techniques so that colloid scientists can decide whether it is suitab le for their particular application.