Particle size determination by automated microscopical imaging analysis with comparison to laser diffraction.

A rapid and precise microscopical analysis technique for the determination of particle size distribution has been developed. Particle size distribution was determined with a Carl Zeiss Axioplan microscope equipped with a computer-controlled image analysis system. Area and volume measurements were performed on a number of particles and plotted against Feret's diameter to yield a distribution histogram. This technique was then applied to several compounds of pharmaceutical interest, and the resulting histograms were compared with histograms determined with a laser diffraction instrument. The reproducibility of the microscopical determination was good and the agreement between the two determinations was dependent on the crystalline shape.