Particle size and packing characterization by diffuse light transmission

► Particle size, packing density and blend composition of glass ballotini, microcrystalline cellulose pellets and theophylline granules were studied by diffuse light transmission. ► Light transmission was found to decrease with decreasing particle size and with increasing packing density. The effect of packing density was significant. ► The method proposed can readily provide information on change in the granular sample.