SOP for pH Testing of Ointments – V 2.0

Procedure for pH Testing of Ointments

Department	Quality Control (QC)/Quality Assurance (QA)/Production
SOP No.	SOP/Ointment/062
Supersedes	V 1.0
Page No.	Page X of Y
Issue Date	[Insert Issue Date]
Effective Date	[Insert Effective Date]
Review Date	[Insert Review Date]

1. Purpose

The purpose of this Standard Operating Procedure (SOP) is to define a standardized method for testing the pH of ointments to ensure product stability, compatibility with skin, and compliance with quality specifications.

2. Scope

This SOP applies to all personnel in the Quality Control (QC) and Quality Assurance (QA) departments responsible for conducting pH testing of ointments during formulation development, in-process control, and final batch release.

3. Responsibilities

Quality Control Analyst: Conducts pH testing and records results.
Quality Assurance Personnel: Reviews and approves test results.
Production Supervisor: Ensures that the ointment batches conform to pH specifications.
R&D Team (if applicable): Evaluates formulation modifications based on pH test results.

4. Accountability

The QC and QA Managers are accountable for ensuring that pH tests are conducted accurately and documented as per regulatory and GMP standards.

5. Procedure

5.1 Equipment and Materials

Calibrated pH meter
Buffer solutions (pH 4.0, 7.0, and 10.0)
Purified water
Glass beaker (100 mL)
Magnetic stirrer (if required)
pH electrode
Data recording sheets

5.2 Pre-Test Preparations

Ensure the pH meter is calibrated before testing.
Prepare a fresh sample by dispersing ointment in purified water (typically 10% w/w dispersion).
Ensure the pH probe is clean and properly immersed in the sample.

5.3 Calibration of pH Meter

Calibrate the pH meter using pH 4.0 and pH 7.0 buffer solutions.
Rinse the electrode with purified water after calibration.
Verify calibration by testing with pH 10.0 buffer (if required).

5.4 pH Measurement

Weigh 10 g of ointment and transfer it into a 100 mL beaker.
Add 90 mL of purified water and mix thoroughly to form a homogeneous dispersion.
Insert the pH electrode into the dispersion.
Allow the reading to stabilize for at least 30 seconds.
Record the final pH value.
Repeat the test in triplicate and calculate the average pH.

5.5 Acceptance Criteria

The pH should be within the predefined range for the specific ointment formulation (e.g., 4.5 – 7.5).
Deviations from the standard range require further investigation and corrective action.

5.6 Documentation

Record all pH measurements in the pH Test Log.
Document instrument calibration details.
QA personnel must review and approve results before batch release.

6. Abbreviations

GMP – Good Manufacturing Practices
QA – Quality Assurance
QC – Quality Control
w/w – Weight/Weight

7. Documents

pH Test Log (Annexure-1)
Ointment Batch Testing Report (Annexure-2)

8. References

WHO GMP Guidelines for Pharmaceutical Manufacturing
USP <791> – pH Determination
ICH Q2 (R1) – Validation of Analytical Procedures

9. SOP Version

Version 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: pH Test Log

Date	Batch Number	Sample Weight (g)	pH Value	Result	Verified By
01/02/2025	OINT-101	10	6.2	Pass	QA Officer
02/02/2025	OINT-102	10	6.5	Pass	QA Officer

Annexure-2: Ointment Batch Testing Report

Date	Batch Number	Test Method	Acceptance Criteria	Result	Final Status	Approved By
01/02/2025	OINT-101	pH Meter	4.5 – 7.5	6.2	Approved	QA Head
02/02/2025	OINT-102	pH Meter	4.5 – 7.5	6.5	Approved	QA Head

12. Revision History:

Revision Date	Revision No.	Details of Revision	Reason for Revision	Approved By
01/01/2024	1.0	Initial Version	New SOP	QA Head
01/02/2025	2.0	Updated SOP Format	Standardization of Document	QA Head