Detecting the Presence of Anomolous Large Particles Within Powders Using Laser Diffraction Particle Size Analysis

The capability of the Mastersizer 3000 and Aero S dispersion unit to measure small quantities of dry powders has been established in a separate application note. Valid concerns when measuring such a small sample are that a) it is not representative of the bulk and b) small amounts of oversized particles may not be detected. Such oversized particles have the potential to cause problems with powder handling, dissolution rates and the bioavailability of active pharmaceutical ingredients.

In this application note, we demonstrate the ability of the Mastersizer 3000 and Aero S dispersion unit to detect a small proportion of anomalously large particles added to a small aliquot in a 'seeding' experiment. We have chosen a fine grade of lactose as a model for pharmaceutical API or excipient powders. This lactose has a Dv (50) of 4μm. The anomalous particles will be a known sample of glass beads with a Dv (50) of 62μm, Malvern’s Quality Audit Standard (QAS).