Practitioner's Report

Accreditation and Quality Assurance

, Volume 17, Issue 2, pp 139-146

First online:

The estimation and use of measurement uncertainty for a drug substance test procedure validated according to USP <1225>

  • M. L. Jane WeitzelAffiliated withQuality Analysis Consultants Email author 

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The vision for metrology at the United States Pharmacopeia (USP) is for international recognition, harmonization, and official acceptance of all USP reference standards that are based on sound, scientific, metrological principles, such as measurement uncertainty (MU). Pharmaceutical testing laboratories will need to estimate the MU for their test procedures. This paper demonstrates how to estimate MU for a test procedure validated following the requirements in USP General Chapter <1225>, Validation of Compendial Procedures. The test procedure determines the assay and impurities for a pharmaceutical drug substance. Pharmaceutical manufacturing companies are required to test the drug substance used in their drug products. In this example, a new test procedure was developed and validated following the requirements in USP <1225>. The MU was estimated using the data from the test procedure validation. The MU estimate determined that the test procedure was fit for use with one determination, avoiding the expense of duplicate determinations. The MU estimate was used to set up decision rules for comparing test data to the assay and impurity specifications. The information from the MU estimate was used to monitor the routine use of the test procedure using control charts that assess accuracy and precision of each run based upon actual test procedure performance capability.


Drug substance Estimation Reporting United States Pharmacopeia