Monitoring the stability of an emulsion by high-frequency spectroscopy

High-frequency spectroscopy has been applied to monitoring the stability of oil-in-water emulsions. It was found that stable emulsions showed absorption peaks at around 550 MHz; further, they shifted from lower to higher frequencies with time. The rate of increase of the frequencies was dependent on the amount of emulsifier added. These results show that the stability of emulsions can be monitored by the amount of the frequency shift.