microbial contamination, and organic impurities in accordance with USP, Ph. Eur., and IP standards.

2. Scope

This SOP is applicable to the Analytical Method Development and Quality Control departments for routine and validation testing of WFI in pharmaceutical manufacturing facilities.

3. Responsibilities

• Analytical Chemist: Performs physical, chemical, and TOC analysis of WFI samples.
• Microbiologist: Conducts microbial limit tests and endotoxin testing.
• QA Executive: Verifies and approves WFI testing reports and ensures compliance with pharmacopeial specifications.

4. Accountability

The Head of Analytical Method Development is accountable for ensuring validated testing methods for WFI are implemented, and all testing conforms to current GMP and pharmacopeial guidelines.

5. Procedure

5.1 Sampling

1. Collect WFI samples aseptically in sterile, pyrogen-free containers.
2. Label all containers with sample location, date, and time of collection.
3. Test immediately or within validated holding time (typically ≤ 4 hours).

5.2 Physicochemical Testing

1. Appearance: Clear, colorless liquid.
2. Conductivity: NMT 1.3 µS/cm at 25°C.
3. pH: Between 5.0 and 7.0 (as per pharmacopeial method).
4. Total Organic Carbon (TOC): NMT 500 ppb (µg/L), tested using TOC analyzer.
5. Nitrate and Heavy Metals: Should be absent or below detection limits as per specifications.

5.3 Microbiological Testing

1. Total Viable Aerobic Count: NMT 10 CFU/100 mL using membrane filtration method.
2. Bacterial Endotoxins Test (BET): NMT 0.25 EU/mL, using kinetic turbidimetric LAL method (Annexure-2).

5.4 Acceptance Criteria

• All physicochemical and microbial parameters must meet USP/Ph. Eur./IP limits.
• Failure in any parameter requires deviation investigation and retesting.

5.5 Method Validation Parameters

1. Specificity: No interference in TOC and conductivity from sampling material or container.
2. Precision: RSD ≤ 2% for replicate TOC and conductivity readings.
3. Accuracy: TOC recovery within 85–115% of spiked standard.
4. Limit of Detection: Below 100 ppb for TOC.

6. Abbreviations

• WFI: Water for Injection
• TOC: Total Organic Carbon
• BET: Bacterial Endotoxins Test
• EU: Endotoxin Units
• CFU: Colony Forming Units

7. Documents

1. WFI Test Record Sheet – Annexure-1
2. Endotoxin Test Report – Annexure-2
3. Validation Summary Report – Annexure-3

8. References

• USP <1231>: Water for Pharmaceutical Purposes
• Ph. Eur. 0169: Water for Injections
• IP Monograph: Water for Injection
• ICH Q2(R1): Validation of Analytical Procedures

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name	Priya Menon	Sachin Deshmukh	Sunita Reddy
Designation	Analytical Scientist	QA Reviewer	Head – AMD
Department	Analytical Method Development	QA	Analytical Method Development

11. Annexures

Annexure-1: WFI Test Record Sheet

Sample Location	Conductivity (µS/cm)	TOC (ppb)	pH	Status
Loop A – Point 1	1.1	212	5.8	Pass

Annexure-2: Endotoxin Test Report

Sample ID	BET Method	Result (EU/mL)	Status
WFI-272-01	Kinetic Turbidimetric	0.05	Pass

Annexure-3: Validation Summary Report

The WFI quality testing procedure was validated as per USP <1231> and Ph. Eur. 0169. TOC analysis, conductivity, and endotoxin testing met all acceptance criteria. The method is robust, reproducible, and suitable for routine monitoring.

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
21/05/2025	2.0	Included TOC validation and BET updates	Annual Review	Sunita Reddy
10/04/2022	1.0	Initial SOP Release	New SOP	QA Head