Formation, Characterization and Stability of Nanoemulsions Prepared by Phase Inversion

Formation and stability of n-undecane in water nanoemulsions prepared by EIP method (Emulsion Inversion Point) in the presence of two nonionic surfactants were studied. In the study, the influences of surfactant concentration, HLB value and oil–to–water ratio on the particle size and distribution were investigated. The stability of emulsions was evaluated from changes in particle size distribution determined by photon correlation spectroscopy, and by visual and microscopy description of their appearance. The results obtained indicate that all the above mentioned variables significantly influence particle size and distribution. It is obvious that for given oil phase, the optimum HLB value of 10.5 exists, at which the emulsion particle size is the smallest at all studied oil-to-water ratios (5/95, 10/90, 15/85, 20/80, 25/75, 30/70). The HLB values above and below optimum then induce the increase of particle size of the studied emulsions. The best emulsion stability was observed for samples stored at the temperature of 4 °C. Key-Words: Emulsion, Hydrophile-lipophile balance, Nanoemulsion, Photon correlation spectroscopy, Stability