Popis: |
The validity of prediction of shelf stability from ultracentrifugal parameters determined on newly prepared Nujol-in-water emulsions stabilized with sodium dodecylsulfate (0.2 to 0.4%), cetylpyridiniumchloride (0.1 to 0.2%), Triton X-100 (0.08 to 0.4%), or Tween 20 (0.08 to 0.4%) was tested by allowing samples to age for periods up to 3 yr. They were then reexamined visually, and an empirical rating scheme devised for describing their stability semiquantitatively. In some cases it was also possible to redetermine the ultracentrifugal parameters on the aged emulsions. None of the ultracentrifugal parameters of the fresh emulsions predicted the order of actual shelf stability correctly in all cases. Possible reasons for the discrepancies are discussed. |