development and stability testing follow appropriate safety protocols and use PPE.

4. Accountability

The Manufacturing Manager is accountable for ensuring that stability-indicating assays are developed and validated according to this SOP. The overall compliance with this SOP is overseen by the Quality Assurance (QA) Manager.

5. Procedure

5.1. Assay Method Selection

1. Identify the active ingredients, degradation products, and potential impurities in the aerosol formulation that need to be monitored over time.
2. Select the appropriate analytical technique(s) for stability testing based on the nature of the formulation, such as:
   • High-performance liquid chromatography (HPLC)
   • Gas chromatography (GC)
   • UV-visible spectroscopy
   • Mass spectrometry (MS)
3. Ensure that the chosen method is capable of detecting small changes in concentration and can distinguish between the active ingredient and degradation products or impurities.
4. Document the selected method and its rationale for use in the assay development process.

5.2. Assay Method Development

1. Develop the assay method by optimizing the following parameters:
   • Sample preparation procedures
   • Chromatographic conditions (e.g., column type, mobile phase, flow rate)
   • Detection sensitivity and selectivity
   • Retention time for active ingredients and degradation products
2. Ensure that the method is capable of measuring the required parameters accurately and reproducibly across the expected range of concentrations.
3. Develop a validation plan for the method, including precision, accuracy, specificity, and limit of detection (LOD) testing.

5.3. Assay Validation

1. Validate the assay method according to the following criteria:
   • Specificity: Confirm that the method can distinguish between the active ingredient and any impurities or degradation products in the formulation.
   • Precision: Evaluate the reproducibility of the results by conducting multiple tests under the same conditions.
   • Accuracy: Determine the accuracy of the assay by comparing the results with known standards or reference materials.
   • Linearity: Ensure that the assay provides a linear response over the expected concentration range.
   • Limit of Detection (LOD): Determine the minimum concentration of the active ingredient or degradation products that can be reliably detected.
2. Document the validation results, including any modifications made to the method during the validation process, in the Assay Validation Report (Annexure-1).

5.4. Stability Testing

1. Conduct stability testing of the aerosol formulation using the validated stability-indicating assay. This involves storing the aerosol product under specified conditions (e.g., temperature, humidity, light) and periodically sampling the product for analysis.
2. Monitor changes in the concentration of active ingredients and the formation of degradation products over time.
3. Record all observations, including storage conditions, sampling dates, and assay results, in the Stability Testing Log (Annexure-2).
4. Compare the results with predefined acceptance criteria to assess the stability and shelf life of the aerosol product.

5.5. Documentation and Record-Keeping

1. Document all assay development activities, including the selection process, method development, validation, and stability testing, in the Assay Development Log (Annexure-3).
2. Ensure that the results of assay validation and stability testing are reviewed by the QC team and signed off for compliance.
3. Store all records in the document management system for future reference and audits.

5.6. Safety and Environmental Considerations

1. Ensure that all laboratory personnel conducting the stability-indicating assay development and testing are trained in proper laboratory safety procedures and the use of PPE.
2. Follow appropriate safety guidelines for handling chemicals, solvents, and aerosol formulations, particularly with respect to their storage, disposal, and potential hazards.
3. Dispose of any waste generated during assay development and stability testing, including used solvents, reagents, or samples, according to the company’s waste disposal procedures and environmental regulations.

6. Abbreviations

• GMP: Good Manufacturing Practice
• QC: Quality Control
• PPE: Personal Protective Equipment
• SOP: Standard Operating Procedure
• LOD: Limit of Detection

7. Documents

1. Assay Development Log (Annexure-3)
2. Assay Validation Report (Annexure-1)
3. Stability Testing Log (Annexure-2)

8. References

This SOP is based on the following regulatory guidelines and industry standards:

• Good Manufacturing Practice (GMP) Guidelines
• FDA Code of Federal Regulations (CFR) Title 21, Part 211
• International Conference on Harmonisation (ICH) Guidelines for Stability Testing
• ISO 9001:2015 – Quality Management Systems

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Assay Validation Report

Assay ID	Validation Date	Validation Results	Operator Name	Remarks
ASSAY-12345	06/02/2025	Pass	Rajesh Patel	No issues found

Annexure-2: Stability Testing Log

Formulation ID	Test Date	Storage Conditions	Test Results	Operator Name	Remarks
FORM-12345	06/02/2025	25°C, 60% RH	No degradation	Rajesh Patel	Passed stability test

Annexure-3: Assay Development Log

Assay ID	Development Date	Method Chosen	Operator Name	Remarks
ASSAY-12345	06/02/2025	HPLC	Rajesh Patel	Method developed and validated

12. Revision History:

Revision Date	Revision No.	Revision Details	Reason for Revision	Approved By	Page No.	Ref. Point No.	Details of Revision
01/01/2024	V 1.0	Initial Release	First Issue	Anjali Sharma	Page 1	[Ref Point]	First Release
01/01/2025	V 2.0	Updated stability-indicating assay procedure	To comply with updated GMP regulations	Anjali Sharma	Page 1	[Ref Point]	Updated procedures