In this application note, Malvern Panalytical measures aliquots as small as 5mg of fine grade, pharmaceutical lactose and show that the measurement reproducibility is well-within the International Standards Organisation (ISO) laser diffraction standard guidelines on repeatability.

This fine grade of lactose was chosen as both an established model material for active pharmaceutical ingredients and as a highly cohesive powder that is difficult to disperse.

The routine measurement of particle size plays an important role in pharmaceutical
and other industries, where it is often a critical-to-quality attribute for the product.

Dispersion is critical for any particle size measurement and two principle routes are
available in laser diffraction systems, wet and dry. If the powder is processed in a dry
state and the end product is a dry powder, then a dry dispersion method is generally
preferred.