Standard Operating Procedure for Use of Handheld pH/Conductivity Meters in API Manufacturing
| Department | API Manufacturing |
|---|---|
| SOP No. | SOP/API/109/2025 |
| Supersedes | SOP/API/109/2022 |
| Page No. | Page 1 of 10 |
| Issue Date | 13/04/2025 |
| Effective Date | 15/04/2025 |
| Review Date | 13/04/2026 |
1. Purpose
To establish a standardized method for using handheld pH and conductivity meters to perform in-process checks during API manufacturing. This ensures consistency in monitoring critical quality attributes and compliance with GMP.
2. Scope
This SOP applies to all handheld pH and conductivity meters used by production and QC personnel for routine monitoring of process solutions, intermediate checks, and final
rinse verification.
3. Responsibilities
- Production Chemist: Perform pH/conductivity measurements, record readings, clean and store equipment.
- QC Analyst: Provide calibration solutions and verify accuracy of instruments used by production.
- QA Officer: Review logbooks for accuracy and compliance with SOP requirements.
4. Accountability
The Production Head is accountable for ensuring correct use of handheld meters. The QA Head is responsible for compliance with GMP documentation and data integrity.
5. Procedure
5.1 Pre-Use Verification
- Check calibration status on label. Do not use if expired or overdue for calibration.
- Ensure meter and probe are free from visible damage or residue.
- Switch on meter and allow to stabilize for 1–2 minutes before use.
5.2 Calibration (If Required)
- Use certified standard buffer solutions (for pH) and standard conductivity solutions.
- Perform two-point calibration for pH (e.g., pH 4.0 and 7.0) and one-point for conductivity.
- Document calibration details in the Equipment Calibration Logbook.
5.3 Measurement Procedure
- Rinse electrode/probe with distilled water or process solvent compatible with the sample.
- Immerse the probe into the sample container or reaction mass, ensuring full contact.
- Wait until the reading stabilizes. Do not record fluctuating values.
- Record the measurement, temperature, and time in the IPC logbook or BMR.
- Repeat readings if result deviates from expected trend or acceptance range.
5.4 Post-Use Cleaning
- Rinse probe with distilled water or appropriate solvent.
- Store pH electrode in storage solution (if applicable) to prevent drying.
- Switch off meter and store in designated safe place to avoid contamination or breakage.
5.5 Troubleshooting
- If readings are inconsistent or error appears:
- Recalibrate using fresh standards
- Inspect cable connections and battery status
- Replace probe if needed and document replacement
5.6 Documentation
- Record the following:
- Date and Time of Measurement
- Batch No.
- Stage (e.g., neutralization, washing)
- Measured pH or Conductivity
- Operator Initials
- Use the format provided in Annexure-1 for IPC entry.
6. Abbreviations
- SOP: Standard Operating Procedure
- QA: Quality Assurance
- QC: Quality Control
- pH: Potential of Hydrogen
- IPC: In-Process Control
7. Documents
- Handheld Meter Usage Log (Annexure-1)
- Equipment Calibration Logbook
- BMR/IPC Data Sheets
8. References
- ICH Q7 – GMP Guidelines for API
- USP General Chapter <791> – pH
- 21 CFR Part 211 – cGMP for Finished Pharmaceuticals
9. SOP Version
Version: 2.0
10. Approval Section
| Prepared By | Checked By | Approved By | |
|---|---|---|---|
| Signature | |||
| Date | |||
| Name | |||
| Designation | |||
| Department |
11. Annexures
Annexure-1: Handheld Meter Usage Log
| Date | Batch No. | Stage | pH/Conductivity | Temperature | Operator | Remarks |
|---|---|---|---|---|---|---|
| 13/04/2025 | API-20250413 | Neutralization | 6.85 | 27.5°C | Ravi Kumar | Within range |
Revision History:
| Revision Date | Revision No. | Details | Reason | Approved By |
|---|---|---|---|---|
| 01/01/2022 | 1.0 | Initial SOP Release | Compliance | QA Head |
| 13/04/2025 | 2.0 | Expanded cleaning and troubleshooting steps | GMP Audit Update | QA Head |