Certificate of analysis
A certificate of analysis (COA) is a document that reports the test methods used, the limits applied and the actual results for a tested material, such as an ingredient a supplier ships to a manufacturer.
What it means in practice
US manufacturing rules for supplements spell out what a supplier's COA must contain if a manufacturer relies on it: a description of the test or examination methods used, the limits of those tests, and the actual results [2].
The same rule limits how far a COA can be used. A manufacturer must run at least one appropriate test or examination to verify the identity of each dietary ingredient itself, unless FDA grants an exemption on petition [2]. For confirming the identity of other components, and for checking whether components meet their other specifications, it may either test them or rely on the supplier's COA [2]. Relying on the COA is allowed only if the manufacturer first qualifies the supplier by confirming the supplier's results, keeps records of how it did so, periodically re-confirms the supplier's COA, and has its quality control staff review and approve that record [2].
Why it matters when reading nootropics research
Labels and contents do not always match. In one 2017 laboratory analysis of commercial melatonin natural health products and supplements, measured melatonin ranged from -83% to +478% of the labeled amount [1] (details under label claim). A COA is one way to see what was measured in a given material, by which method, and against which limits.
A COA covers the sample that was tested, and a COA a brand publishes about its own product is company-reported information. It speaks to contents, not to whether an ingredient has shown an effect against placebo in trials. On NootropicsWork, a company's COA is cited as the company's own statement, with the date it was captured.
References
- Erland LA, Saxena PK. Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content. J Clin Sleep Med. 2017.
- Electronic Code of Federal Regulations (eCFR). 21 CFR 111.75 What must you do to determine whether specifications are met?. eCFR title 21 up to date as of 2026-11-09.