SOP Guide for Pharma

Elixir Department: SOP for Specific Gravity Testing – V 2.0

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Elixir Department: SOP for Specific Gravity Testing – V 2.0

Standard Operating Procedure for Specific Gravity Testing of Elixir Formulations

Department Elixir Department
SOP No. SOP/ELX/224/2025
Supersedes SOP/ELX/224/2022
Page No. Page 1 of 7
Issue Date 11/04/2025
Effective Date 15/04/2025
Review Date 11/04/2026

1. Purpose

To provide a standardized method for determining the specific gravity of elixir formulations using a pycnometer or digital density meter, ensuring batch-to-batch consistency and compliance with product specifications.

2. Scope

This SOP applies to all elixir formulations tested in the Quality Control Laboratory for specific gravity determination as part of in-process and finished product testing.

3. Responsibilities

  • QC Analyst:
    • Perform the specific gravity test using the prescribed method and record data.
  • QC Supervisor:
    • Ensure proper calibration of instruments and verification of test results.
  • QA Officer:
    • Review and approve the specific gravity data for batch release.
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4. Accountability

The QC Head is accountable for ensuring accurate execution of this test. The QA Head ensures compliance with established specifications and regulatory standards.

5. Procedure

5.1 Equipment and Materials

  • Calibrated pycnometer (25 mL or 50 mL)
  • Digital density
meter (optional)
  • Analytical balance (calibrated)
  • Water bath maintained at 25°C ± 0.5°C
  • Thermometer (calibrated)

    • 5.2 Method Using Pycnometer

    1. Clean and dry the pycnometer thoroughly.
    2. Weigh the empty, dry pycnometer (W1).
    3. Fill the pycnometer with purified water at 25°C. Weigh (W2).
    4. Empty, dry, and then fill the pycnometer with the test sample at 25°C. Weigh again (W3).
    5. Calculate specific gravity using the formula:
      Specific Gravity = (W3 – W1) / (W2 – W1)

    5.3 Method Using Digital Density Meter

    1. Calibrate the instrument using purified water at 25°C.
    2. Inject the test sample into the U-tube and measure the specific gravity directly as displayed.
    3. Repeat measurement in duplicate and take average.

    5.4 Acceptance Criteria

    1. Specific gravity should comply with the specification stated in the product’s approved specification (e.g., 1.05–1.15).
    2. Results must not deviate by more than ±0.01 from historical batch average without investigation.

    5.5 Documentation

    1. Record all weights and calculations in the Specific Gravity Test Logbook (Annexure-1).
    2. Attach instrument printouts (if applicable) and retain in the batch file.

    6. Abbreviations

    • SOP: Standard Operating Procedure
    • QC: Quality Control
    • QA: Quality Assurance
    • W1: Weight of empty pycnometer
    • W2: Weight of pycnometer with water
    • W3: Weight of pycnometer with sample

    7. Documents

    1. Specific Gravity Test Logbook (Annexure-1)
    2. Instrument Calibration Records
    3. Batch Manufacturing Record (BMR)

    8. References

    • USP Chapter <841> – Specific Gravity
    • Ph. Eur. 2.2.5 – Relative Density
    • 21 CFR Part 211.165 – Testing and Release for Distribution

    9. SOP Version

    Version: 2.0

    10. Approval Section

    Prepared By Checked By Approved By
    Signature
    Date
    Name
    Designation
    Department

    11. Annexures

    Annexure-1: Specific Gravity Test Logbook

    Date Batch No. W1 (g) W2 (g) W3 (g) Calculated SG Specification Tested By Verified By
    11/04/2025 ELX-0425-042 25.00 50.00 53.75 1.15 1.05–1.15 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 method and updated limits Method Harmonization QA Head
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