both in-house and pharmacopeial reference-based working standards.

3. Responsibilities

• QC Analyst: Prepare and qualify working standards using approved procedures.
• QC Supervisor: Review and approve working standard preparation records.
• QA Officer: Ensure traceability, proper labeling, and expiry management.

4. Accountability

The Head – Quality Control is accountable for the preparation, storage, verification, and documentation of all working standards used in analytical operations.

5. Procedure

5.1 Preparation of Working Standards

1. Obtain a qualified reference standard with valid CoA and expiry date.
2. Weigh an accurately known amount (e.g., 100 mg) of reference standard using a calibrated balance.
3. Dilute with a suitable solvent or buffer to a known concentration (e.g., 1000 µg/mL) using volumetric glassware.
4. Label the working standard solution with:
   • Working Standard Code (e.g., WS-API-001)
   • API name
   • Concentration
   • Date of preparation
   • Prepared by
   • Expiry date

5.2 Qualification

1. Compare the working standard with the reference standard using appropriate tests:
   • Assay by HPLC/UV
   • Identity by IR, TLC, or other validated techniques
2. Calculate the correction factor or purity value if applicable.
3. Record results in the Working Standard Qualification Report (Annexure-1).
4. Approve the standard for routine use only if all results are within acceptable criteria.

5.3 Storage Conditions

1. Store solid working standards in amber-colored, airtight containers with desiccant.
2. Store solution standards in amber-colored vials at recommended conditions (e.g., 2–8°C or as defined in STP).
3. Do not use beyond the assigned expiry date or if discoloration/precipitation is observed.

5.4 Usage and Expiry

1. Use working standards only for the analysis for which they are qualified.
2. Assign a validity of ≤ 6 months from the date of preparation unless otherwise justified.
3. Document each use in the Working Standard Usage Log (Annexure-2).

5.5 Disposal

1. Discard expired or disqualified working standards following the SOP for chemical waste disposal.
2. Record disposal details in the Working Standard Destruction Log (Annexure-3).

6. Abbreviations

• API: Active Pharmaceutical Ingredient
• WS: Working Standard
• QC: Quality Control
• QA: Quality Assurance
• HPLC: High Performance Liquid Chromatography
• IR: Infrared Spectroscopy

7. Documents

1. Working Standard Qualification Report (Annexure-1)
2. Working Standard Usage Log (Annexure-2)
3. Working Standard Destruction Log (Annexure-3)
4. STP and Reference Standard CoA

8. References

• ICH Q7 – Good Manufacturing Practice Guide for Active Pharmaceutical Ingredients
• 21 CFR Part 211 – US FDA cGMP Guidelines
• Pharmacopoeial Monographs (USP, BP, IP)

9. SOP Version

Version: 2.0

10. Approval Section

	Prepared By	Checked By	Approved By
Signature
Date
Name
Designation
Department

11. Annexures

Annexure-1: Working Standard Qualification Report

Date	WS Code	API Name	Reference Std	Assay (%)	Test Performed	Qualified
13/04/2025	WS-API-002	Metronidazole	RS-API-005	99.3%	HPLC/IR	Yes

Annexure-2: Working Standard Usage Log

Date	WS Code	Batch No.	Test Type	Used By	Remarks
14/04/2025	WS-API-002	API-20250413	Assay	Sunita Reddy	Used within expiry

Annexure-3: Working Standard Destruction Log

Date	WS Code	Reason	Quantity Discarded	Disposed By	Verified By
15/04/2025	WS-API-001	Expired	150 mg	Ravi Kumar	Rajesh Sharma

Revision History:

Revision Date	Revision No.	Details	Reason	Approved By
01/01/2022	1.0	Initial SOP	GMP Compliance	QA Head
13/04/2025	2.0	Added usage logs and destruction documentation	Audit Requirement	QA Head