Triboelectrification of pharmaceutically relevant powders during low-shear tumble blending

A test apparatus and methods used to study the influence of physical properties of pharmaceutically relevant powders and powder mixtures on triboelectric behavior during low-shear blending is described. Samples were mixed using a stainless steel blender and dispensed directly into a Faraday pail to measure charge. Eight different materials commonly used in pharmaceutical solid dosage formulation were characterized. Particle size and known concentrations of discrete particle size distributions were shown to influence the measured surface charge densities consistent with previously reported results. Further, binary mixtures of the model compounds were studied and found to produce unanticipated trends in surface charge density. The effectiveness of process parameters, including hold time after processing, and formulation design in controlling the surface charge density in particulate systems is also discussed with supporting results obtained from the proposed apparatus.