Light-scattering method in particle size analysis of parenteral emulsions

The use of a light-scattering particle size distribution analyzer has been shown to be a convenient method for characterizing the particle size distribution of parenteral emulsions. However, the concentrations of the samples used were found to have a major impact on the particle size distribution results, particularly for samples with a mean particle size smaller than 0.2 micron. An increase in sample concentration caused a shift to smaller particle sizes as a result of multiple scattering. The blue-light (tungsten lamp) intensity, instead of the He-Ne laser integrity, should be used to control sample concentration within the optimal range for measurement.