consistency in formulation performance and shelf-life.

2. Scope

This SOP is applicable to the Analytical Method Development (AMD) and Quality Control (QC) departments for the evaluation of phase separation in gel-based pharmaceutical formulations during development, scale-up, and stability studies.

3. Responsibilities

• Analytical Scientist: Performs phase separation testing using centrifugation and visual techniques.
• QC Analyst: Maintains sample storage logs and documents observations.
• QA Executive: Reviews and verifies test data and ensures protocol adherence.

4. Accountability

The Head of Analytical Method Development is accountable for ensuring accurate and reproducible testing of gel formulations for phase separation, and for the validation of the methodology.

5. Procedure

5.1 Materials and Equipment

1. Calibrated centrifuge (3000–5000 rpm)
2. Glass tubes (centrifuge compatible)
3. Refrigerator (-20°C), incubator (40°C)
4. Vernier caliper or scale
5. Digital camera for documentation

5.2 Sample Preparation

1. Dispense 10 g of gel into clean centrifuge tubes (duplicate or triplicate).
2. Ensure samples are free from air bubbles and represent the bulk formulation.

5.3 Centrifugation Test

1. Centrifuge samples at 4000 rpm for 30 minutes at ambient temperature.
2. Inspect samples for:
   • Visible liquid separation at the top or bottom
   • Discoloration or clumping
   • Change in texture or consistency
3. Document presence and volume of separated phase.

5.4 Freeze-Thaw Cycle Test

1. Subject samples to 6 cycles of freezing at -20°C (24 hours) followed by thawing at 25°C (24 hours).
2. Visually inspect after each cycle and document any:
   • Phase separation
   • Opacity changes
   • Loss of gel integrity

5.5 Long-Term Storage Observation

1. Store samples at 25°C / 60% RH and 40°C / 75% RH.
2. Evaluate monthly for up to 6 months for physical changes.

5.6 Acceptance Criteria

• No phase separation or liquefaction post-centrifugation.
• No significant visual change after 6 freeze-thaw cycles.
• Changes in color, clarity, and texture must be within pre-defined formulation tolerances.

5.7 Method Validation Parameters

1. Repeatability: Phase separation results must be reproducible within triplicates.
2. Robustness: Phase stability must hold under centrifugation, thermal stress, and cycling.

6. Abbreviations

• RH: Relative Humidity
• QA: Quality Assurance
• AMD: Analytical Method Development

7. Documents

1. Phase Separation Observation Log – Annexure-1
2. Freeze-Thaw Stability Log – Annexure-2
3. Validation Summary Report – Annexure-3

8. References

• WHO TRS on Stability Testing for Semisolid Dosage Forms
• ICH Q1A(R2): Stability Testing Guidelines
• FDA Guidance: Scale-up and Post-Approval Changes for Semisolid Drug Products

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name	Ananya Mishra	Jignesh Patel	Sunita Reddy
Designation	Analytical Chemist	QA Reviewer	Head – AMD
Department	Analytical Method Development	QA	Analytical Method Development

11. Annexures

Annexure-1: Phase Separation Observation Log

Sample ID	Post-Centrifuge Observation	Volume of Separation (mL)	Status
GEL-264-01	No separation	0	Pass

Annexure-2: Freeze-Thaw Stability Log

Cycle No.	Condition	Appearance	Status
6	-20°C to 25°C	No phase change	Pass

Annexure-3: Validation Summary Report

The method for detection of phase separation in gels was validated across three formulations. Results were reproducible and no separation was observed under centrifugation and freeze-thaw conditions. The method is suitable for routine use in physical stability evaluation.

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
21/05/2025	2.0	Included freeze-thaw cycle protocol and updated acceptance criteria	Annual Review	Sunita Reddy
05/04/2022	1.0	Initial Release	New SOP	QA Head