Ultrasonic Spectroscopy Study of Globule Aggregation in Parenteral Fat Emulsions Containing Calcium Chloride

Ultrasonic attenuation spectroscopy has been used to study globule aggregation in parenteral fat emulsions. The ultrasonic attenuation spectrum (from 1 to 100 MHz) of a 12 vol % parenteral emulsion was measured at 25 °C. Globule aggregation was then induced in the emulsion by titrating with calcium chloride (0−3.28 mM CaCl 2 ). Dramatic changes in the attenuation spectrum of the emulsion were observed when the globules aggregated, which could be attributed to changes in either the spatial distribution (flocculation) or the size distribution (coalescence) of the globules. The change in globule size during aggregation was calculated using ultrasonic scattering theory assuming that the aggregates are spherical and have properties similar to those of the disperse phase. Ultrasonics has advantages over many other technologies because it can be used to analyze emulsions that are concentrated and optically opaque in situ.