Published · Updated · 6 min read
How to Read a Certificate of Analysis
A practical guide to batch numbers, test methods, specifications and numerical results on a certificate of analysis.
Short answer
A useful certificate of analysis connects one identified batch to a named laboratory, stated specifications, test methods and actual results. Match the batch number on the certificate to the package before reviewing any result.
What is a certificate of analysis?
A certificate of analysis, commonly shortened to COA or C of A, is a laboratory document reporting tests performed on a specific material or batch. It is evidence about the tested sample, not a general promise about every unit ever produced.
Health Canada's GMP guide defines a certificate of analysis as a document that includes the testing laboratory, material specifications, tests, methods, numerical results, approval information and other necessary technical details.
Check these fields first
Start with identity and traceability before interpreting technical results.
- Product or material name that matches the listing.
- Batch or lot number that matches the package.
- Laboratory name and contact information.
- Sample receipt, testing and approval dates.
- Test method and specification for each reported result.
- Actual numerical results, not only a generic pass statement.
What does assay mean?
An assay estimates how much of the target substance is present relative to a stated specification. The result only has meaning beside its unit, acceptance range and test method. A percentage without those details is incomplete context.
Identity, assay, purity and contaminant testing answer different questions. One passing assay result does not automatically establish every other quality characteristic.
What a COA cannot tell you
A COA does not provide medical advice, establish that a product is appropriate for a particular person, or replace regulatory authorization. It also cannot describe a different lot unless the document explicitly covers that lot.
If a certificate and package do not share the same batch number, treat them as unrelated until the supplier resolves the mismatch.
Primary sources
- Health Canada: Good manufacturing practices guide for drug products
- FDA: Import for Export, certificate of analysis examples
This guide is general product-documentation information, not medical advice. Regulatory records can change; verify current information with the linked authority.