Responsibilities

• Production Chemist: Perform pH adjustment and document the activity.
• Quality Assurance (QA): Monitor and verify pH adjustments and ensure GMP compliance.
• Head – Manufacturing: Ensure overall compliance and availability of required equipment and solutions.

4. Accountability

The Head of Gel Manufacturing is accountable for implementation and adherence to this SOP.

5. Procedure

5.1 Pre-requisites

1. Ensure that all necessary equipment, such as calibrated pH meters and stirrers, are available and functional.
2. Verify that the batch has reached the pH adjustment stage as per BMR.
3. Ensure QA has granted line clearance for pH adjustment activities.

5.2 pH Measurement

1. Withdraw a representative sample (approx. 10g) of the gel using a sanitized spatula.
2. Place the sample in a clean beaker and dilute with an equal amount of purified water to facilitate measurement.
3. Immerse the calibrated pH probe and allow reading to stabilize.
4. Record the pH value in the BMR.

5.3 pH Adjustment Procedure

1. If pH is outside specified limits (e.g., 5.0–7.0), prepare appropriate neutralizing solution:
   • Triethanolamine (TEA) for upward adjustment
   • Citric Acid or Lactic Acid solution for downward adjustment
2. Slowly add the neutralizing solution dropwise to the bulk gel under continuous stirring.
3. After each addition (approximately 1 ml per 10 kg), allow homogenization for 5–10 minutes before rechecking pH.
4. Repeat until pH reaches the acceptable range.
5. Document quantity and type of pH adjuster used in BMR.

5.4 Post Adjustment Verification

1. Once pH is within the acceptable range, conduct a final check and document the reading.
2. QA personnel to cross-verify pH and provide authorization to proceed with the next process step.

5.5 Precautions

• Always wear appropriate PPE (gloves, goggles, apron) during handling of acidic/alkaline pH adjusters.
• Never add concentrated acids or bases directly to the gel without proper dilution.
• Use freshly prepared solutions for accuracy and safety.

6. Abbreviations

• BMR: Batch Manufacturing Record
• GMP: Good Manufacturing Practices
• QA: Quality Assurance
• PPE: Personal Protective Equipment

7. Documents

1. Batch Manufacturing Record – Annexure-1
2. pH Meter Calibration Log – Annexure-2
3. pH Adjustment Log Sheet – Annexure-3

8. References

• ICH Q7 Good Manufacturing Practices
• Schedule M – GMP Requirements
• Indian Pharmacopoeia (IP) Specifications

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: Batch Manufacturing Record

Detailed steps and records related to pH measurement and adjustment.

Annexure-2: pH Meter Calibration Log

Details of pH meter calibration status and history.

Annexure-3: pH Adjustment Log Sheet

Logs of pH before and after each adjustment, type and quantity of solution used, and operator initials.

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
01/05/2022	1.0	Initial Issue	First SOP Release	QA Head
02/06/2025	2.0	Included new pH adjustment range and updated safety instructions	Annual SOP Review	QA Head