Reflectance measurements on gels and emulsions containing cetrimide and cetostearyl alcohol--a preliminary investigation.

Various light scattering properties-the reflectivity, contrast ratio and scattering index of a series of gels and emulsions containing cetrimide, cetostearyl alcohol, water and liquid paraffin have been examined using reflectance measurements made at 560 nm using a four-filter, tristimulus colorimeter. The scattering properties of both systems were dependent on the total interfacial surface area of either the dispersed unreacted cetostearyl alcohol and/or the dispersed droplets of liquid paraffin, and hence increased with increasing concentration of both ingredients. For the emulsion containing liquid paraffin, the scattering properties increased linearly with the concentration of liquid paraffin but with the ternary gel system the scattering properties were not directly related to cetostearyl alcohol concentration. This was confirmed by microscopy as due to the changes in the size of the dispersed unreacted cetostearyl alcohol. The results illustrate the potential of this simple, reproducible non-destructive technique in the study of the structure of such systems.