Standard Operating Procedure for Angle of Repose Testing in Granules

1) Purpose

The purpose of this SOP is to outline the procedure for determining the angle of repose of granule formulations in the pharmaceutical industry to assess their flow properties and particle cohesion.

2) Scope

This SOP applies to all personnel involved in angle of repose testing of granule formulations within the pharmaceutical quality control (QC) department.

3) Responsibilities

Analytical Chemist: Responsible for performing angle of repose testing and documenting results.
Quality Assurance (QA) Department: Responsible for reviewing and approving the angle of repose testing procedure and results.

4) Procedure

1. Sample Collection:
   1. Select representative samples from different batches or lots according to the sampling plan.
   2. Ensure samples are free from large aggregates and particles.
2. Apparatus Setup:
   1. Set up the angle of repose apparatus on a stable and level surface.
   2. Adjust the height of the funnel to achieve the desired diameter of the powder cone.
3. Testing:
   1. Pour the granule sample through the funnel onto the base plate, forming a cone.
   2. Allow the granules to flow freely until no further movement is observed.
   3. Measure the height (h) and radius (r) of the formed cone.
4. Calculation:
   1. Calculate the angle of repose using the formula:
   2. Angle of Repose (θ) = tan-1 (h / r)
   3. Where:
      • h is the height