Standard Operating Procedure for Analytical Balance Calibration in API Manufacturing
| Department | API Manufacturing |
|---|---|
| SOP No. | SOP/API/123/2025 |
| Supersedes | SOP/API/123/2022 |
| Page No. | Page 1 of 9 |
| Issue Date | 13/04/2025 |
| Effective Date | 15/04/2025 |
| Review Date | 13/04/2026 |
1. Purpose
To lay down the procedure for internal and external calibration of analytical balances used in the Quality Control (QC) laboratory to ensure that all weighing performed is accurate and traceable to national standards.
2. Scope
This SOP applies to all analytical balances used in the QC lab for the analysis of raw materials, intermediates, and finished APIs. It includes
both daily calibration checks and scheduled external calibration by certified agencies.
3. Responsibilities
- QC Chemist: Perform daily internal calibration checks and document results.
- QC Executive: Review calibration records and report any deviations.
- External Calibration Vendor: Carry out certified calibration as per annual schedule.
4. Accountability
The Head – QC is accountable for ensuring that all balances are calibrated as per defined schedules and are suitable for analytical use.
5. Procedure
5.1 Internal (Daily) Calibration
- Use certified calibration weights traceable to national standards (e.g., 10 mg, 50 mg, 100 mg, 200 mg, 500 mg, 1000 mg).
- Ensure the balance is leveled and on vibration-free surface before use.
- Check the zero reading of the balance before placing any weight.
- Place each standard weight and record the displayed value.
- Compare the result with the actual weight and calculate the deviation.
- Deviation should be within ±0.2 mg for 1 mg readability and ±0.1% for higher weights.
- Document the results in the Daily Balance Calibration Logbook (Annexure-1).
5.2 External Calibration
- Performed semi-annually or annually by a government-approved or NABL-accredited external agency.
- Ensure the calibration certificate includes:
- Calibration date
- Serial number of the balance
- Calibration range and results
- Uncertainty of measurement
- Authorized signature
- Attach calibration certificate in the balance file and update the Calibration Schedule Tracker.
5.3 Out-of-Tolerance Handling
- If deviation exceeds acceptable limits:
- Tag the balance as “Out of Service”
- Stop using the balance for any weighing
- Inform the QC Manager immediately
- Initiate corrective action and impact assessment for results generated since last calibration
5.4 Precautions
- Do not touch standard weights with bare hands; use forceps or gloves.
- Store standard weights in their original containers when not in use.
- Do not place samples directly on balance pan; use clean containers or weighing paper.
- Clean the balance pan before and after use with a lint-free cloth.
6. Abbreviations
- SOP: Standard Operating Procedure
- QC: Quality Control
- NABL: National Accreditation Board for Testing and Calibration Laboratories
- OOS: Out of Specification
7. Documents
- Daily Balance Calibration Logbook (Annexure-1)
- External Calibration Certificate
- Calibration Schedule Tracker
8. References
- USP <41> – Weights and Balances
- 21 CFR Part 211 – US FDA GMP
- ICH Q7 – GMP for APIs
- ISO/IEC 17025 – General requirements for testing and calibration laboratories
9. SOP Version
Version: 2.0
10. Approval Section
| Prepared By | Checked By | Approved By | |
|---|---|---|---|
| Signature | |||
| Date | |||
| Name | |||
| Designation | |||
| Department |
11. Annexures
Annexure-1: Daily Balance Calibration Logbook
| Date | Balance ID | Weight Used | Displayed Value | Deviation | Result (Pass/Fail) | Checked By |
|---|---|---|---|---|---|---|
| 13/04/2025 | QC-BAL-03 | 100 mg | 100.2 mg | +0.2 mg | Pass | Sunita Reddy |
Revision History:
| Revision Date | Revision No. | Details | Reason | Approved By |
|---|---|---|---|---|
| 01/01/2022 | 1.0 | Initial Issue | New SOP | QA Head |
| 13/04/2025 | 2.0 | Included out-of-tolerance and precautions section | Audit Compliance | QA Head |