Elixir Department: SOP for Inline pH Meter Operation – V 2.0

Standard Operating Procedure for Inline pH Meter Operation in Elixir Manufacturing

Department	Elixir Department
SOP No.	SOP/ELX/129/2025
Supersedes	SOP/ELX/129/2022
Page No.	Page 1 of 10
Issue Date	11/04/2025
Effective Date	15/04/2025
Review Date	11/04/2026

1. Purpose

To establish a standard procedure for the operation, calibration, and maintenance of inline pH meters used in elixir manufacturing to ensure accurate and real-time pH monitoring during product formulation and adjustment processes.

2. Scope

This SOP applies to all inline pH meters installed in process tanks, transfer lines, or recirculation loops used during the manufacturing of elixirs in the Elixir Department.

3. Responsibilities

Production Operator:
- Operate and monitor the inline pH meter during batch processes.
- Ensure calibration is performed prior to use as per schedule.
Production Supervisor:
- Verify calibration records and ensure deviations are reported and resolved.
Engineering Department:
- Perform periodic preventive maintenance and probe replacement.
QA Officer:
- Review calibration, maintenance logs, and ensure adherence to GMP.

4. Accountability

The Production Head is accountable for the effective use of the inline pH meter and the Engineering Head is accountable for maintaining its operational integrity.

5. Procedure

5.1 Pre-Operation Checks

Verify that the inline pH meter is labeled “CALIBRATED” and not due for the next calibration.
Check probe cleanliness, absence of air bubbles, and proper immersion in the product stream.
Ensure the meter is connected to the display/control unit and the power supply is active.

5.2 Calibration Procedure

Disconnect the pH probe from the process line, rinse with distilled water, and immerse in pH 7.0 buffer solution.
Allow the reading to stabilize and adjust the meter if deviation is observed.
Repeat the process with pH 4.0 and pH 10.0 buffer solutions for 3-point calibration.
Rinse probe thoroughly after calibration and reconnect to process line.
Document calibration in the pH Meter Calibration Log (Annexure-1).

5.3 Operational Use During Batch

Monitor the pH value on the digital display throughout the mixing and blending operations.
Log pH readings in the BMR at intervals specified in the manufacturing instructions (e.g., every 10 minutes).
In case of pH deviation:
- Pause addition of raw materials
- Check calibration status
- Adjust pH using buffers as per approved process

5.4 Cleaning and Maintenance

After batch completion, clean the probe with distilled water or neutral detergent if specified.
If required, use pH electrode cleaning solution followed by rinsing with purified water.
Inspect and document probe wear or damage; replace if necessary.

5.5 Safety and Precautions

Never touch the pH probe glass bulb directly with bare hands.
Always store pH probes in a suitable storage solution when not in use for long durations.
Do not use expired buffer solutions for calibration.

6. Abbreviations

SOP: Standard Operating Procedure
QA: Quality Assurance
BMR: Batch Manufacturing Record
GMP: Good Manufacturing Practice

7. Documents

pH Meter Calibration Log (Annexure-1)
Preventive Maintenance Log
Batch Manufacturing Record

8. References

ICH Q8 – Pharmaceutical Development
21 CFR Part 211 – cGMP for Finished Pharmaceuticals
USP General Chapter <791> – pH

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 Meter Calibration Log

Date	Equipment ID	pH 4.0 Reading	pH 7.0 Reading	pH 10.0 Reading	Calibrated By	Remarks
11/04/2025	PHM-09	4.02	6.98	10.01	Sunita Reddy	Acceptable

Revision History:

Revision Date	Revision No.	Revision Details	Reason for Revision	Approved By
01/01/2024	1.0	Initial SOP Release	New SOP	QA Head
11/04/2025	2.0	Added 3-point calibration method and precautions	Process Improvement	QA Head