The word stability is ambiguous in colloidal science and means different things for different people. In suspoemulsions or concentrates it is possible to identify at least three different physical processes which may lead to instability in a particulate system. For example change in particle size may be due to Ostwald's ripening, particle aggregation and particle sedimentation. Therefore an understanding of behavior of fine particles, and their interactions with the inert ingredients in a suspoemulsion or suspension formulation is necessary to develop a stable formulation. The behavior of these fine particles in aqueous suspoemulsion is a cumulative function of electrostatic, steric and hydrophobic interactions with the inert ingredients and other physical processes.
This paper discusses the processes and techniques involved in the stabilization of suspoemulsion / suspension concentrates. A Model pesticidal formulations was chosen to study the effect of surfactant system on the stability of the formulation and its dilution performance. Further attempts were made to correlate the physical long term stability of the formulation with change in particle size, distribution and Zeta potential measurements.