Powder Testing

Introduction  

The widespread use of powders in the pharmaceutical industry has led to a proliferation of test methods for measuring powder flow and density.

The new harmonised chapters in the Pharmacopoeias on Powder Flow (USP Chapter <1174> and Ph.Eur. 2.9.36) list four well defined methods for powder testing aimed at trying to bring about some degree of standardisation within the test methodology:

• Flow through an orifice
• Angle of Repose
• Shear Cell
• Compressibility Index and Hausner Ratio

The new Flowability Tester BEP2 provides a range of options for testing pharmaceutical powders including three of the four methods quoted in the Pharmacopoeias – flow through an orifice, angle of repose and shear cell – in a single, cost effective unit.

For compressibility index and Hausner ratio testing, we offer a series of tapped density testers and the bulk density tester (Scott Volumeter), detailed monographs for which feature in USP Chapter <616> and Ph.Eur. Chapter 2.9.15.

For comprehensive product details, specifications and part numbers, please request a copy of our brochure “Quality Solutions for the Testing of Pharmaceuticals”.

Bulk Density

The bulk density of powders can be extremely difficult to measure since the slightest disturbance may cause a change in the results.

This is the consequence of the relationship between the particles that constitute the powder bulk. This same relationship affects the ability of the powder to flow.

The bulk density of a powder is measured in a Scott Volumeter. It may be described as the density of the powder “as poured” into a measuring vessel.

Tapped density, on the other hand, is the density attained after “tamping down”. This is normally measured using an instrument that lifts and then drops a measuring cylinder containing the powder through a fixed distance.

For comprehensive product details, specifications and part numbers, please request a copy of our brochure “Quality Solutions for the Testing of Pharmaceuticals”.