How to read a certificate of analysis
Learn what a COA can and cannot establish: sample identity, batch traceability, methods, specifications, results and important testing gaps.
For research and education only. These introductions do not establish safety, regulatory approval or suitability for personal use, and are not medical advice.
Start with the sample and the report
A certificate of analysis, or COA, records test results for an identified sample or batch. Check the material name, batch or lot identifier, reporting laboratory, report date and who submitted the sample. A genuine report still needs a traceable connection to the material being discussed.
FDA's Q7 guidance for active pharmaceutical ingredient manufacturing describes certificates with batch identification, the tests performed, acceptance limits and numerical results where applicable. That is a useful reading framework, not a claim that any particular vendor meets pharmaceutical manufacturing requirements.
Separate the test, the limit and the result
Identity asks what was detected. Assay estimates how much of a target is present under a specified method. A chromatographic purity result describes a measured distribution of signals under that method. These are not automatically the same measurement.
For example, a hypothetical report might list an acceptance limit of at least 98.0% and a result of 98.7%. That meets that stated limit for that test only. It does not show that every possible impurity was measured, or that 98.7% of the entire contents has been independently established as the target compound.
Look for what was not tested
Do not interpret an absent test as a passing result. Residual solvents, elemental impurities, water content, microbiological contamination and endotoxins are different analytical questions. Which tests matter depends on the material and the intended regulated context.
Ask how the laboratory verified identity, which method and reference standard were used, and whether the report can be authenticated with the laboratory. A COA alone does not establish sterility, clinical effectiveness, legal status or safety for human use.
Sources & further reading
Browse free educational tools — calculations do not verify sample quality
Public education guides
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