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

1. Use a fixed funnel method on a flat surface.
2. Allow powder to flow through a funnel positioned at a fixed height (6 cm) above the surface.
3. Measure height (h) and radius (r) of the cone formed.
4. Calculate angle of repose using the formula:
   θ = tan⁻¹(h/r)
5. Perform the test in triplicate and report average.

5.2 Bulk and Tapped Density

1. Weigh 50 g of powder and pour into a 100 mL graduated cylinder without compacting.
2. Record initial volume as bulk volume (V_b).
3. Tap the cylinder 500 times using a tapped density tester or manually, until volume stabilizes (V_t).
4. Calculate:
   • Bulk density (g/mL) = Weight / V_b
   • Tapped density (g/mL) = Weight / V_t

5.3 Compressibility Index and Hausner Ratio

1. Calculate Compressibility Index (%) using:
   
   CI = [(Tapped density – Bulk density) / Tapped density] × 100
2. 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
• V_b: Bulk Volume
• V_t: Tapped Volume

7. Documents

1. Flow Property Test Sheet – Annexure-1
2. Density Calculation Log – Annexure-2
3. 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