Standard Operating Procedure for pH Adjustment Analysis in Enteric-Coating Materials
| Department | Quality Control |
|---|---|
| SOP No. | SOP/TAB/104/2025 |
| Supersedes | SOP/TAB/104/2022 |
| Page No. | Page 1 of 6 |
| Issue Date | 01/03/2026 |
| Effective Date | 06/03/2026 |
| Review Date | 01/03/2027 |
1. Purpose
To define the procedure for performing pH adjustment analysis in enteric-coating materials, ensuring that the pH of the coating solution is within the specified range for proper coating formation.
2. Scope
This SOP applies to the pH adjustment analysis of enteric-coating materials used in tablet coating processes. It ensures that the pH level of the coating solution meets the requirements for effective enteric coating.
3. Responsibilities
- Quality Control (QC): Responsible for performing the pH adjustment analysis of the enteric-coating solution and ensuring that the pH level is within the specified limits.
- Quality Assurance (QA): Ensures that the pH adjustment procedure is followed correctly and reviews the results for compliance with product specifications.
- Coating Operators: Responsible for preparing the enteric-coating solution and adjusting the pH to meet the required standards.
4. Accountability
The QC Manager is accountable for ensuring that the pH adjustment analysis is carried out correctly and that the pH values fall within the specified range. The QA Manager is responsible for approving the results and ensuring compliance with regulatory standards.
5. Procedure
5.1 Preparation of Coating Solution
- Prepare the enteric-coating solution according to the formulation and the coating process specifications.
- Ensure all required excipients and materials are available and properly mixed to prepare the coating solution.
- Before adjusting the pH, check the initial pH of the solution using a calibrated pH meter.
5.2 pH Adjustment
- If the pH is outside the desired range, adjust the pH using appropriate acid or alkali solutions (e.g., citric acid, sodium hydroxide) to bring the solution into the specified pH range for enteric coating (typically pH 4.5–5.5, but as per formulation requirements).
- Stir the solution continuously to ensure uniform distribution of the pH-adjusting agents.
- After each addition, measure the pH again using the calibrated pH meter until the target pH is achieved.
5.3 pH Verification
- Once the target pH is reached, verify the pH level with multiple readings from different areas of the coating solution.
- Record the final pH value in the batch record (Annexure-1).
- If the pH remains stable and within the acceptable range, proceed with the coating process. If not, re-evaluate the solution and repeat the pH adjustment process.
5.4 Documentation and Record-Keeping
- Document all pH adjustments and final pH values in the batch record (Annexure-1), including the reagents used and the amounts added during pH adjustment.
- Ensure that all records are signed, dated, and stored according to the company’s record retention policy for future audits and inspections.
5.5 Post-Adjustment Actions
- Once the pH is adjusted and documented, proceed with the coating process or store the solution as per the process requirements.
- Dispose of any pH adjustment reagents according to the company’s waste disposal procedures.
6. Abbreviations
- SOP: Standard Operating Procedure
- GMP: Good Manufacturing Practice
- QC: Quality Control
- QA: Quality Assurance
- pH: Potential of Hydrogen
7. Documents
- Batch Record (Annexure-1)
- Deviation Report (Annexure-2)
8. References
- USP <1225> – Pharmaceutical Dosage Forms: Coating
- 21 CFR Part 211 – Current Good Manufacturing Practice for Finished Pharmaceuticals (US FDA)
- European Pharmacopoeia (EP) – Coating Material Specifications
9. SOP Version
Version: 2.0
10. Approval Section
| Prepared By | Checked By | Approved By | |
|---|---|---|---|
| Signature | |||
| Date | |||
| Name | |||
| Designation | |||
| Department |
11. Annexures
Annexure-1: Batch Record
| Batch Number | Coating Solution pH | Reagents Used | Amount Added | Final pH | Remarks |
|---|---|---|---|---|---|
| Batch 001 | 4.2 | Citric acid | 50 mL | 4.8 | Pass |
Annexure-2: Deviation Report
| Deviation Date | Batch Number | Deviation Description | Corrective Action | Responsible Person |
|---|---|---|---|---|
| 15/12/2025 | Batch 001 | pH adjustment exceeded limit | Re-adjusted pH to 4.8 | John Doe |
Revision History:
| Revision Date | Revision No. | Revision Details | Reason for Revision | Approved By |
|---|---|---|---|---|
| 01/01/2024 | 1.0 | Initial Version | New SOP Creation | QA Head |
| 01/02/2025 | 2.0 | Updated pH adjustment procedure | Refined reagent usage for pH control | QA Head |