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 |