Standard Operating Procedure for pH Testing of Injectable Products
| Department | Sterile Injectable Manufacturing |
|---|---|
| SOP No. | SOP/SIM/064/2025 |
| Supersedes | SOP/SIM/064/2022 |
| Page No. | Page 1 of 12 |
| Issue Date | 18/06/2025 |
| Effective Date | 20/06/2025 |
| Review Date | 18/06/2026 |
1. Purpose
This SOP defines the procedure for testing the pH of sterile injectable products to ensure the solution maintains a pH range that meets pharmacopeial requirements and is safe for administration.
2. Scope
This procedure applies to all batches of sterile injectable formulations manufactured at [Company Name], including
in-process and final product stages.
3. Responsibilities
- QC Analyst: Responsible for performing the pH testing using a calibrated pH meter.
- QC Supervisor: Reviews and verifies results.
- QA Officer: Ensures compliance with specifications before batch release.
4. Accountability
The Head of Quality Control is accountable for the execution and compliance of this SOP.
5. Procedure
5.1 Equipment and Materials
- Calibrated pH meter
- pH standard buffer solutions (4.01, 7.00, and 9.21)
- Beakers, pipettes, gloves, and clean wipes
5.2 Calibration of pH Meter
- Switch on the pH meter and allow it to stabilize.
- Calibrate using standard buffer solutions as per the instrument SOP.
- Ensure a minimum two-point calibration (pH 4.01 and 7.00 or 7.00 and 9.21).
- Record calibration data in the pH Meter Calibration Log (Annexure-1).
5.3 Sample Preparation
- Withdraw a representative sample of the injectable product.
- For powders, reconstitute using specified diluent per product monograph.
- Allow the sample to reach room temperature (20°C to 25°C).
5.4 Testing Procedure
- Rinse the electrode with distilled water and blot dry using lint-free tissue.
- Immerse the electrode in the sample ensuring full contact with the solution.
- Record the pH value once stabilized (typically within 30 seconds).
- Rinse and dry the electrode after each sample.
- Repeat testing in duplicate for accuracy.
5.5 Acceptance Criteria
The pH value should comply with the specifications mentioned in the approved product monograph or pharmacopoeia (e.g., USP, EP, IP).
5.6 Documentation
- Record all readings in the pH Testing Log (Annexure-2).
- Attach signed test report with Batch Release Form (Annexure-3).
6. Abbreviations
- SOP: Standard Operating Procedure
- QC: Quality Control
- pH: Potential of Hydrogen
- USP: United States Pharmacopeia
- EP: European Pharmacopoeia
- IP: Indian Pharmacopoeia
7. Documents
- pH Meter Calibration Log – Annexure-1
- pH Testing Log – Annexure-2
- Batch Release Form – Annexure-3
8. References
- USP General Chapter <791> – pH
- EP 2.2.3 – Potentiometric Determination of pH
- IP – pH Determination Procedures
9. SOP Version
Version: 2.0
10. Approval Section
| Prepared By | Checked By | Approved By | |
|---|---|---|---|
| Signature | |||
| Date | |||
| Name | |||
| Designation | QC Analyst | QC Manager | Head QA |
| Department | Quality Control | Quality Control | Quality Assurance |
11. Annexures
Annexure-1: pH Meter Calibration Log
| Date | Instrument ID | Buffer pH Used | Calibrated By | Remarks |
|---|---|---|---|---|
| 18/06/2025 | PHM-02 | 4.01 / 7.00 | Ajay Deshmukh | Calibration OK |
Annexure-2: pH Testing Log
| Batch No. | Product | pH Value | Tested By | Date |
|---|---|---|---|---|
| CFT-124 | Ceftriaxone Injection | 6.5 | Neha Patil | 18/06/2025 |
Annexure-3: Batch Release Form
| Product | Batch No. | pH Complies | Reviewed By | QA Release |
|---|---|---|---|---|
| Meropenem Injection | MERP-007 | Yes | Sunita Reddy | Approved |
Revision History
| Revision Date | Revision No. | Details | Reason | Approved By |
|---|---|---|---|---|
| 02/01/2022 | 1.0 | Initial version | New SOP | QA Head |
| 18/06/2025 | 2.0 | Updated procedure and annexures | Periodic Review | QA Head |