Scope

This SOP applies to all personnel involved in using, calibrating, and maintaining pH meters for in-process and final product testing during gel manufacturing activities in the pharmaceutical plant.

3. Responsibilities

• Production Operator: Performs pH measurements and basic care of the instrument.
• Production Supervisor: Ensures adherence to SOP and reviews records.
• QA Executive: Performs periodic checks, reviews calibration records, and verifies compliance.
• Engineering/Maintenance Team: Responsible for troubleshooting, repairs, and preventive maintenance.

4. Accountability

The Head – Manufacturing shall ensure implementation, training, and strict adherence to this SOP.

5. Procedure

5.1 General Precautions

• Handle pH electrodes with care; avoid dropping or applying force.
• Use gloves while handling calibration solutions and gel samples.
• Calibrate the pH meter daily or before every batch measurement.
• Ensure that the meter and electrode are properly cleaned before use.

5.2 Pre-Operational Checks

1. Verify that the pH meter is in “Ready to Use” status.
2. Ensure buffer solutions (typically pH 4.0, 7.0, and 9.2) are not expired and are at room temperature.
3. Check for any visible damage or residue on the electrode.

5.3 Calibration Procedure

1. Switch on the pH meter and allow it to stabilize for 5 minutes.
2. Rinse the electrode with distilled water and blot gently with a lint-free tissue.
3. Immerse the electrode into pH 7.0 buffer solution. Allow the reading to stabilize and press “Calibrate”.
4. Repeat the above steps using pH 4.0 and 9.2 buffer solutions for 2-point or 3-point calibration.
5. Record calibration details in Annexure-1.

5.4 pH Measurement of Gel Samples

1. Rinse the electrode with distilled water.
2. Immerse the electrode in the gel sample in a clean beaker with adequate depth.
3. Stir the sample gently to avoid entrapment of air bubbles.
4. Allow the reading to stabilize (usually 30–60 seconds).
5. Record the pH value in the Batch Manufacturing Record (BMR) and Annexure-2.
6. Rinse the electrode thoroughly between samples to avoid cross-contamination.

5.5 Post-Measurement Care

1. Clean the electrode with distilled water and store it in electrode storage solution.
2. Do not store electrodes dry or submerged in distilled water.
3. Switch off the pH meter when not in use and cover it with a dust shield.

5.6 Equipment Maintenance

• Perform monthly maintenance including inspection of cables and connectors.
• Replace the electrode every 6–12 months or as recommended by the manufacturer.
• Record maintenance details in equipment logbook.

6. Abbreviations

• BMR: Batch Manufacturing Record
• QA: Quality Assurance
• SOP: Standard Operating Procedure
• PPE: Personal Protective Equipment

7. Documents

1. pH Meter Calibration Log – Annexure-1
2. pH Testing Record – Annexure-2
3. Equipment Cleaning Log
4. Batch Manufacturing Record (BMR)

8. References

• ICH Q7: Good Manufacturing Practice Guide for Active Pharmaceutical Ingredients
• Manufacturer’s Manual for Digital pH Meter

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: pH Meter Calibration Log

Date	Equipment ID	Buffer pH Used	Observed Value	Calibrated By	Remarks
		pH 4.0 / 7.0 / 9.2

Annexure-2: pH Testing Record

Date	Batch No.	Product Name	Sample Type (In-Process/Final)	pH Observed	Tested By	Remarks

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
01/05/2022	1.0	Initial version	New SOP	QA Head
02/06/2025	2.0	Expanded procedure and annexure details	Periodic Review	QA Head