ABSTRACT
Particle size analysis has been the subject of a number of excellent texts. Particle size clearly plays a role in formulation development. Real particle populations consist of heterogeneous mixtures. Individually classifying particles by size, from smallest to largest, may result in a shift in shape, surface rugosity, and energetics. The description of particle populations requires adoption of mathematical descriptors of the entire distribution of sizes. The characteristic dimension of a particle requires definitions of terms. Since most particles are irregularly shaped, the common practice is to consider equivalent spherical dimensions based on a particular feature such as volume, surface area, or projected area diameters. Lognormal distributions are derived from the normal distribution of the logarithms of the particle sizes. Mathematical and statistical functions in their simplest forms may not accurately approximate the data. Indeed, sophisticated approaches are required for multimodal data analysis.
