Elixir Department: SOP for Conductivity Testing – V 2.0

Standard Operating Procedure for Conductivity Testing in Elixir Formulations

Department	Elixir Department
SOP No.	SOP/ELX/232/2025
Supersedes	SOP/ELX/232/2022
Page No.	Page 1 of 7
Issue Date	11/04/2025
Effective Date	15/04/2025
Review Date	11/04/2026

1. Purpose

To define a standardized procedure for measuring the electrical conductivity of elixir formulations, which is indicative of ionic strength, formulation consistency, and water quality used during manufacturing.

2. Scope

This SOP applies to the Quality Control Department for routine and stability testing of elixirs, and for verification of purified water and solution conductivity during formulation and packaging operations.

3. Responsibilities

QC Analyst:
- Calibrate the conductivity meter, perform the test, and document the results.
QC Supervisor:
- Review test results, ensure compliance with product specification, and check instrument calibration records.
QA Officer:
- Ensure regulatory compliance and verification of test documentation for batch release.

4. Accountability

The QC Head is accountable for ensuring accuracy and consistency in conductivity testing. The QA Head is responsible for verifying compliance with GMP and pharmacopeial standards.

5. Procedure

5.1 Equipment and Materials

Conductivity

meter with temperature compensation

Conductivity cell (with known cell constant)

Conductivity standard solution (e.g., 84 µS/cm, 1413 µS/cm)

Sample container (clean, dry, and conductivity-tested)

Purified water (for rinsing and blanks)

5.2 Calibration

Calibrate the conductivity meter using standard solutions traceable to NIST.
Rinse the electrode with purified water between different standards.
Document the calibration data in the instrument calibration logbook.

5.3 Sample Preparation

Allow the elixir sample to equilibrate to room temperature (25 ± 2°C).
Transfer sufficient quantity (minimum 50 mL) into the rinsed test beaker.
Ensure there are no bubbles in the sample before testing.

5.4 Conductivity Measurement

Immerse the conductivity probe in the sample.
Allow reading to stabilize and record the conductivity in µS/cm.
If temperature compensation is manual, adjust reading based on the temperature correction chart.
Perform the test in duplicate and report the average value.

5.5 Acceptance Criteria

Conductivity should be within specified limits (e.g., 200–800 µS/cm depending on formulation).
For purified water used in elixirs: NMT 1.3 µS/cm at 25°C (as per USP).
Any value outside limits should be investigated and documented as per deviation management SOP.

5.6 Documentation

Record the sample identification, conductivity, temperature, and result in the Conductivity Logbook (Annexure-1).
Attach instrument printouts where applicable.
Ensure date, batch number, and analyst signatures are captured accurately.

6. Abbreviations

SOP: Standard Operating Procedure
USP: United States Pharmacopeia
µS/cm: Microsiemens per centimeter
QC: Quality Control
QA: Quality Assurance

7. Documents

Conductivity Logbook (Annexure-1)
Instrument Calibration Log
Batch Manufacturing Record (BMR)

8. References

USP Chapter <645> – Water Conductivity
21 CFR Part 211.160 – Laboratory Controls
ICH Q6A – Specifications: Test Procedures and Acceptance Criteria

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Conductivity Logbook

Date	Batch No.	Conductivity (µS/cm)	Temperature (°C)	Specification	Pass/Fail	Tested By	Verified By
11/04/2025	ELX-0425-049	525	25.1	200–800	Pass	Rajesh Kumar	Sunita Reddy

Revision History:

Revision Date	Revision No.	Revision Details	Reason for Revision	Approved By
01/01/2024	1.0	Initial SOP Release	New SOP Creation	QA Head
11/04/2025	2.0	Updated method validation and water specification reference	Regulatory Alignment	QA Head