Reporting Results of Pharmaceutical Impurities: A Case Study

Reporting Results of Pharmaceutical Impurities

In addition to specification/limit, the detection limit (DL) of impurities, the quantification limit (QL) must also be considered when reporting pharmaceutical impurity results. Impurity data should be presented in a clear, structured, and accurate manner to ensure regulatory compliance and data integrity

Expert Tips

• Don’t integrate the impurity peaks having a value less than DL (detection limit)
• Integrate the impurity peaks having a value more than or equal to DL (detection limit) limit)
• Impurities having a value less than or equal to QL (quantification) should not be included in the total impurities
• Impurities having a value more than or equal to QL (quantification) should be included in the total impurities

Case Study: Certificate of Analysis (CoA)-Impurities Section

Product Name: [e.g., Paracetamol]
Batch Number: [e.g., ab123]
Date of Analysis: [e.g., 18-06-2025]
Test Method Reference: [e.g., In-house HPLC Method No. xyz]

Note:

• DL = 0.01%
• QL = 0.03%

Expert Tips:

1. Results should differentiate known and unknown impurities.
2. Use validated analytical methods.
3. Ensure alignment with pharmacopoeial or internal specifications.
4. If reporting to regulatory bodies, specify identification thresholds, reporting thresholds (RL), and qualification thresholds per ICH guidelines.

How do you ensure the accuracy and repeatability of the test results?

In pharmaceutical analysis, accuracy and repeatability are ensured by:

• Using validated analytical methods following ICH or pharmacopeial guidelines.
• Calibrating instruments regularly with certified reference standards.
• Following Good Laboratory Practices (GLP) and Standard Operating Procedures (SOPs).
• Running system suitability tests before sample analysis.
• Performing replicate analyses and calculating %RSD (relative standard deviation) to assess repeatability.
• Using quality control samples and known standards to verify accuracy.
• Maintaining consistent environmental conditions and proper documentation throughout the process.

Related:

1. Relative Response Factor (RRF) in Pharmaceutical Analysis
2. Control of Nitrosamine Impurities in Pharmaceuticals: Learn Easily in 7 Minutes
3. How To Control Impurities In Pharmaceuticals: Get Mastery In 11 Minutes
4. Specified and Unspecified Impurities In APIs: How To Set Limits
5. ICPMS: A Key Tool For Elemental Impurities Analysis in Pharmaceuticals
6. Forced Degradation Studies: How Helpful In Drug Development?
7. What Is Photostability Testing Of New Drug Substances?

Further Reading

Accuracy and repeatability of the test results