confirm the accuracy and consistency of assay and impurity testing in drug development and quality control environments.

2. Scope

This procedure applies to all analytical solutions including standard, sample, diluent, and mobile phases prepared and evaluated by the Analytical Method Development (AMD) department. It is applicable to studies conducted for method validation, transfer, verification, or routine analysis purposes.

3. Responsibilities

• Analyst: Prepares and stores solutions, performs testing, and records observations as per protocol.
• Supervisor: Reviews the solution stability plan and verifies adherence to protocol.
• QA Reviewer: Ensures compliance with SOP and regulatory standards; reviews and archives reports.

4. Accountability

The Head of Analytical Method Development is accountable for verifying that the solution stability studies are executed, reviewed, and documented in accordance with ICH Q2(R1), WHO, and internal regulatory expectations.

5. Procedure

5.1 Planning and Protocol Preparation

1. Draft a solution stability protocol (Annexure-1) that includes:
   • Solution types (e.g., standard, sample, diluent, mobile phase)
   • Storage conditions (room temperature, refrigerated, protected from light)
   • Testing intervals (e.g., 0, 6, 12, 24, 48, 72 hours, 7 days)
   • Acceptance criteria (e.g., peak area difference, retention time, assay results within ±2%)
2. Submit protocol for QA approval prior to initiation.

5.2 Preparation of Solutions

1. Prepare fresh standard and sample solutions according to validated method.
2. Record preparation details: analyst name, date, time, concentration, batch number of reagents/standards.
3. Divide into multiple aliquots stored under intended conditions (e.g., amber vials, refrigerated, light-protected).

5.3 Testing at Defined Time Points

1. At each interval, analyze an aliquot of the stored solution against a freshly prepared reference solution.
2. Evaluate chromatographic parameters such as retention time, resolution, tailing factor, and peak area.
3. Calculate % difference in assay or impurity level compared to the initial time point.

5.4 Data Evaluation and Acceptance

1. Accept solution stability if:
   • Assay results within ±2% of initial
   • No significant impurity peak increase or degradation product formation
   • No change in pH (for pH-sensitive solutions)
   • Chromatographic profile remains comparable
2. Record all observations and results in the Solution Stability Report format (Annexure-2).

5.5 Handling Deviations

1. Document any deviations from the plan (e.g., temperature excursions, delay in testing).
2. Conduct root cause analysis and document in the Deviation and CAPA Log (Annexure-3).
3. Determine impact on data reliability and implement corrective actions.

5.6 Report Preparation and Archival

1. Prepare the final report including summary of results, interpretation, and recommendation on solution hold time.
2. Submit for review and approval by QA.
3. File the report along with raw data in the AMD documentation repository.

6. Abbreviations

• QA: Quality Assurance
• ICH: International Council for Harmonisation
• SOP: Standard Operating Procedure
• CAPA: Corrective and Preventive Action

7. Documents

1. Annexure-1: Solution Stability Study Protocol Template
2. Annexure-2: Solution Stability Data and Report Template
3. Annexure-3: Deviation and CAPA Log Sheet

8. References

• ICH Q2(R1): Validation of Analytical Procedures
• WHO Technical Report Series – Annex on Analytical Methodology
• 21 CFR Part 211.194 – Laboratory Controls

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name	Anjali Bhatnagar	Deepak Mehra	Dr. Sneha Vyas
Designation	Analyst	QA Reviewer	Head – AMD
Department	Analytical Method Development	Quality Assurance	Analytical Method Development

11. Annexures

Annexure-1: Solution Stability Study Protocol Template

Includes objective, solution type, storage condition, test plan, and acceptance criteria.

Annexure-2: Solution Stability Data and Report Template

Details chromatographic data, comparative analysis, calculation sheets, and conclusion.

Annexure-3: Deviation and CAPA Log Sheet

Deviation ID	Description	Root Cause	Corrective Action	Status
DEV-376-01	Delayed testing at 24-hour interval	Instrument scheduling conflict	Revised testing window	Closed

Revision History

Revision Date	Revision No.	Details	Reason	Approved By
01/06/2025	2.0	Included extended testing intervals and clarified acceptance limits	Annual Review	Dr. Sneha Vyas
05/08/2022	1.0	Initial release	New SOP	QA Head