12 - 14 October,
Easing formulation of emulsions and test for long term stability using bottom focussed back scattering
T. Sobisch, U. Rietz, D. Lerche
LUM
Rudower Chaussee 29 (OWZ) 12489
info@lum-gmbh.de, www.lum-gmbh.com
Abstract
Selection of efficient emulsifiers, their optimum concentration and of the processing conditions is a demanding and time consuming process. Evaluation of emulsion stability can be eased when focussing on the changes in droplet concentration right at the bottom part of the emulsion samples. Furthermore the level of the back scattering signal is directly related to the dispersion degree. Thus the initial back scattering signal can be used to compare emulsification quality and to detect loss in dispersity due to aging.
A new multisample approach using light backscattering signals is presented. It allows for fast measurement of stability and/or demixing phenomena and separation kinetics of up to 8 different samples simultaneously, by monitoring the concentration change in a very small region of interest at the bottom of the sample cell.
The method was applied to trace the optimum emulsifier concentrations for silicone oil emulsions to evaluate the influence of processing intensity. Further the method was used to detect the very first changes of sample dispersity after accelerated aging.
Results demonstrate that bottom focussed back scattering can be applied as tool in every day formulation work and that during accelerated aging tests the method can serve as a sensitive measure of loss of dispersion integrity.
Keywords: formulation, emulsifier selection, processing conditions, accelerated aging, bottom focussed back scattering
No comments:
Post a Comment