How to Evaluate a Certificate of Analysis
A practical checklist for matching a COA to a research material and reading the reported methods and results.
Start with identity and traceability
A certificate is useful only when it can be connected to the material in front of you. Compare the product name, lot or batch identifier, sample identifier, quantity or concentration, and analysis date with the listing and physical label.
If the document does not identify the tested sample clearly, ask the supplier to explain the chain between the material and the report before relying on it.
- Product and batch identifiers match
- Laboratory and report date are named
- Sample description is specific
- Report is complete and legible
Read the method before the result
A percentage without a named method does not explain what was measured. HPLC commonly reports chromatographic purity, while mass spectrometry supports molecular-mass or identity assessment. These methods answer different questions and should not be treated as interchangeable.
Check whether the report identifies the instrument or method, preparation conditions, detection approach, acceptance criteria, and who reviewed the result.
Record uncertainties
Do not fill gaps with assumptions. Note missing signatures, unexplained corrections, mismatched identifiers, absent methods, or results that are difficult to interpret. Keep the original report with your procurement record and document questions sent to the supplier.