Read Bachelor of Engineering thesis Monitoring of emulsions using image analysis by Mie Schaldemose in cooperation with ParticleTech and the Technical University of Denmark.
This Bachelor of Engineering thesis was an experimental study on how to monitor emulsion stability with oCelloScope. The experiments were based on the emulsion nucleus of The Continental Method (Briggs et al.,1920) and a hand wash detergent developed by a virtual laboratory (Mattei et al., 2018). The stability of The Continental Method was challenged by varying the concentration of the emulsifying agent. All emulsions were monitored by oCelloScope immediately and after 48 hours of storage. A comparison of the best focus images showed, that at the lowest concentrations of emulsifying agent, the emulsions had become unstable in terms of flocculation. As the concentration of emulsifier increased the level of flocculation decreased. Furthermore, there was an indication of a negative correlation between the droplet diameter and the concentration of emulsifying agent, based on data provided by ParticleTech Analyser Software. These experiments established the foundation of a protocol of monitoring emulsions using oCelloScope. The protocol includes procedures on identification of emulsion type, dilution, specimen preparation and image acquisition with oCelloScope. Experiments with the hand wash detergent and a commercial emulsion was successfully accomplished to validate if the protocol could be considered generic.
This thesis lead to a hypothesis, that has not yet been verified, but will be explained in the following. All results are derived from the thesis.
The graph below indicated a correlation between the concentration of emulsifier and the D50 feret mean of the dispersed phase. It showed a decrease in D50 feret mean as the concentration of emulsifier increased. However, this graph did not give any indication of the stability. To learn about the stability image analysis was required.
All emulsions were monitored after preparation and then again 48 hours later. The images showed that the emulsions at the lowest concentrations of emulsifier had become unstable in terms of flocculation. However, at 20% the emulsions appeared stable. It should be noted that none of the stored samples showed visually evidence of instabilities.
This method can be regarded as an additional and fast way of stability testing when developing emulsions.
The D50 feret mean, measured by the algorithm of the stable emulsion containing 20% emulsifier, could be passed on to the production and used as a part of the quality assurance. The stippled line in the graph below represents the D50 feret mean of the emulsion. If the emulsion had a D50 feret mean above this level the production should for instance, consider to prolong the homogenization process.