at in-process stages, prior to final homogenization and filling.

3. Responsibilities

• Production Officer: Responsible for performing the pH measurement and adjustment as per the defined specifications.
• Quality Control Analyst: Responsible for verifying the pH readings post-adjustment.
• Quality Assurance Executive: Responsible for reviewing the batch documentation and compliance with the process.

4. Accountability

The Manufacturing Head is accountable for the overall adherence and implementation of this SOP.

5. Procedure

5.1 Pre-Adjustment Preparation

1. Ensure pH meter is calibrated as per the current calibration schedule.
2. Verify the availability of buffer solutions and adjusting agents (e.g., citric acid, sodium hydroxide solution).
3. Ensure proper PPE (Personal Protective Equipment) is worn during pH adjustment.

5.2 Sampling for pH Measurement

1. Withdraw approximately 10g of gel formulation from the bulk batch using a sanitized spatula.
2. Transfer to a clean beaker and dilute with purified water (1:10 w/v) if required.
3. Record the batch number, time of sampling, and operator initials.

5.3 Performing pH Adjustment

1. Measure the pH of the sample using the calibrated pH meter.
2. Compare with specification range provided in the BMR (e.g., 5.0–6.5 for carbomer-based gels).
3. If the pH is out of range:
   • Add dropwise the required adjusting agent under continuous stirring.
   • Recheck pH after each incremental addition.
   • Repeat until the target pH is achieved.

5.4 Post-Adjustment Verification

1. Sample the final adjusted batch again and send for QC verification.
2. Attach the pH adjustment record to the BMR.
3. Record observations in the In-Process pH Adjustment Log (Annexure-1).

5.5 Precautions

• Never exceed 0.1% addition of pH adjuster without QA approval.
• Ensure homogeneity post pH adjustment before further processing.
• Label all reagents and glassware involved in pH correction clearly.

6. Abbreviations

• QA: Quality Assurance
• QC: Quality Control
• PPE: Personal Protective Equipment
• BMR: Batch Manufacturing Record

7. Documents

1. In-Process pH Adjustment Log – Annexure-1
2. pH Meter Calibration Certificate – Annexure-2

8. References

• ICH Q8 (R2) – Pharmaceutical Development
• USP General Chapter <795> – Pharmaceutical Compounding

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation	Jr. Production Chemist	QA Executive	Head – Manufacturing
Department	Gel Manufacturing	Quality Assurance	Manufacturing

11. Annexures

Annexure-1: In-Process pH Adjustment Log

Date	Batch No.	Initial pH	Adjustment Performed	Final pH	Operator Signature	QA Verified

Annexure-2: pH Meter Calibration Certificate Template

Instrument Name:	pH Meter
Instrument ID:
Calibration Date:
Calibrated By:
Buffer Solutions Used:	pH 4.0, 7.0, 9.2
Results:
Next Calibration Due:
Remarks:

Revision History

Revision Date	Revision No.	Change Description	Reason	Approved By
05/06/2022	1.0	Initial version	Procedure Release	QA Manager
02/06/2025	2.0	Added log format and calibration record details	Compliance Update	QA Manager