Standard Operating Procedure for Refractive Index Determination in Elixir Formulations
| Department | Elixir Department |
|---|---|
| SOP No. | SOP/ELX/225/2025 |
| Supersedes | SOP/ELX/225/2022 |
| Page No. | Page 1 of 7 |
| Issue Date | 11/04/2025 |
| Effective Date | 15/04/2025 |
| Review Date | 11/04/2026 |
1. Purpose
To establish a standardized procedure for determining the refractive index of elixir formulations using an Abbe refractometer or digital refractometer, ensuring product identity and quality compliance.
2. Scope
This SOP applies to the Quality Control Department for routine and stability testing of refractive index in elixir formulations as part of in-process control and final product analysis.
3. Responsibilities
- QC Analyst:
- Calibrate the instrument, perform the test, and document results.
- QC Supervisor:
- Verify calibration status and review analytical data for accuracy.
- QA Officer:
- Ensure test compliance and release authorization based on specification adherence.
4. Accountability
The QC Head is accountable for the execution and integrity of refractive index testing. The QA Head is responsible for regulatory compliance and final product disposition.
5. Procedure
5.1 Equipment and Materials
- Abbe Refractometer or Digital Refractometer
- Purified Water (for cleaning)
- Standard
Reference Liquids (e.g., nD = 1.3330 for water)
Lint-free tissue or soft cloth
5.2 Calibration
- Clean prism surfaces thoroughly before calibration.
- Use distilled water or certified calibration standards at 25°C.
- Adjust the instrument to read nD = 1.3330 for water at 25°C.
- Record calibration details in the calibration logbook.
5.3 Sample Preparation and Measurement
- Bring the elixir sample to room temperature (25 ± 0.5°C).
- Apply a few drops of the sample onto the prism surface.
- Close the prism cover and allow temperature equilibration (1–2 minutes).
- Read the refractive index displayed (for digital) or adjust till sharp boundary (for Abbe) is visible.
- Record the observed refractive index to four decimal places (e.g., 1.4125).
- Clean the prism after each use with purified water and dry thoroughly.
5.4 Acceptance Criteria
- The refractive index should fall within the approved range stated in the product specification (e.g., 1.4000–1.4200 at 25°C).
- Any deviation beyond limits should be investigated and recorded as per deviation control SOP.
5.5 Documentation
- Enter all readings in the Refractive Index Logbook (Annexure-1).
- Record temperature, instrument ID, batch number, and analyst signature.
- Attach printouts from digital instruments to the Batch Manufacturing Record (BMR) if applicable.
6. Abbreviations
- SOP: Standard Operating Procedure
- QC: Quality Control
- QA: Quality Assurance
- nD: Refractive Index at Sodium D-line (589 nm)
- BMR: Batch Manufacturing Record
7. Documents
- Refractive Index Logbook (Annexure-1)
- Instrument Calibration Logbook
- Batch Manufacturing Record (BMR)
8. References
- USP Chapter <831> – Refractive Index
- Ph. Eur. 2.2.6 – Refractive Index
- 21 CFR Part 211.160 – Laboratory Controls
9. SOP Version
Version: 2.0
10. Approval Section
| Prepared By | Checked By | Approved By | |
|---|---|---|---|
| Signature | |||
| Date | |||
| Name | |||
| Designation | |||
| Department |
11. Annexures
Annexure-1: Refractive Index Logbook
| Date | Batch No. | Temperature (°C) | Observed nD | Specification | Instrument ID | Tested By | Verified By |
|---|---|---|---|---|---|---|---|
| 11/04/2025 | ELX-0425-043 | 25.0 | 1.4112 | 1.4000–1.4200 | RF-01 | 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 | Added digital refractometer process and verification | Method Expansion | QA Head |