Standard Operating Procedure for Flow Property Evaluation of Powders in Analytical Method Development
| Department | Analytical Method Development |
|---|---|
| SOP No. | SOP/AMD/294/2025 |
| Supersedes | SOP/AMD/294/2022 |
| Page No. | Page 1 of 10 |
| Issue Date | 21/05/2025 |
| Effective Date | 23/05/2025 |
| Review Date | 21/05/2026 |
1. Purpose
To define the procedure for evaluating the flow properties of pharmaceutical powders and granules using established parameters such as angle of repose, compressibility index, and Hausner ratio, ensuring
batch suitability for tableting and encapsulation.
2. Scope
This SOP is applicable to the Analytical Method Development and Quality Control departments for routine assessment of powder flow characteristics during formulation development and commercial manufacturing.
3. Responsibilities
- Formulation Scientist: Supplies powder samples and defines critical process parameters.
- Analytical Scientist/QC Analyst: Performs and records flow property evaluations.
- QA Executive: Verifies documentation and ensures compliance with specifications.
4. Accountability
The Head of Analytical Method Development is accountable for ensuring validated flow property testing procedures are used to support quality and processing consistency.
5. Procedure
5.1 Angle of Repose
- Use a fixed funnel method on a flat surface.
- Allow powder to flow through a funnel positioned at a fixed height (6 cm) above the surface.
- Measure height (h) and radius (r) of the cone formed.
- Calculate angle of repose using the formula:
θ = tan⁻¹(h/r) - Perform the test in triplicate and report average.
5.2 Bulk and Tapped Density
- Weigh 50 g of powder and pour into a 100 mL graduated cylinder without compacting.
- Record initial volume as bulk volume (Vb).
- Tap the cylinder 500 times using a tapped density tester or manually, until volume stabilizes (Vt).
- Calculate:
- Bulk density (g/mL) = Weight / Vb
- Tapped density (g/mL) = Weight / Vt
5.3 Compressibility Index and Hausner Ratio
- Calculate Compressibility Index (%) using:
CI = [(Tapped density – Bulk density) / Tapped density] × 100 - Calculate Hausner Ratio using:
HR = Tapped density / Bulk density
5.4 Interpretation of Flow Property
| Test | Excellent | Good | Fair | Poor |
|---|---|---|---|---|
| Angle of Repose | < 25° | 25–30° | 31–35° | > 40° |
| Compressibility Index | < 10% | 11–15% | 16–20% | > 25% |
| Hausner Ratio | < 1.11 | 1.12–1.18 | 1.19–1.25 | > 1.34 |
6. Abbreviations
- CI: Compressibility Index
- HR: Hausner Ratio
- θ: Angle of Repose
- Vb: Bulk Volume
- Vt: Tapped Volume
7. Documents
- Flow Property Test Sheet – Annexure-1
- Density Calculation Log – Annexure-2
- Statistical Summary Report – Annexure-3
8. References
- USP <1174>: Powder Flow
- Ph. Eur. 2.9.36: Powder Flow Properties
- ICH Q6A: Specifications – Test Procedures and Acceptance Criteria
9. SOP Version
Version: 2.0
10. Approval Section
| Prepared By | Checked By | Approved By | |
|---|---|---|---|
| Signature | |||
| Date | |||
| Name | Shweta Nair | Prakash Chauhan | Sunita Reddy |
| Designation | Analytical Chemist | QA Reviewer | Head – AMD |
| Department | Analytical Method Development | QA | Analytical Method Development |
11. Annexures
Annexure-1: Flow Property Test Sheet
| Sample ID | Angle of Repose | CI (%) | HR | Flow Grade |
|---|---|---|---|---|
| FP-294-01 | 28.4° | 13.2% | 1.15 | Good |
Annexure-2: Density Calculation Log
| Weight (g) | Bulk Volume (mL) | Tapped Volume (mL) | Bulk Density | Tapped Density |
|---|---|---|---|---|
| 50.0 | 72.5 | 63.0 | 0.69 g/mL | 0.79 g/mL |
Annexure-3: Statistical Summary Report
Powder exhibits acceptable flow properties with CI 13.2% and HR 1.15, suitable for tablet compression. Data within acceptable variation limits (RSD < 2%).
Revision History:
| Revision Date | Revision No. | Details | Reason | Approved By |
|---|---|---|---|---|
| 21/05/2025 | 2.0 | Included interpretation table and detailed formulas | Annual Review | Sunita Reddy |
| 20/09/2022 | 1.0 | Initial SOP Release | New SOP | QA Head |