Research brief · 2026-09-09
What a Certificate of Analysis Tells You (and What It Can't)
A certificate of analysis, or COA, sounds authoritative. It is a document issued by a laboratory that reports the results of defined tests on a defined batch of material. It describes what was measured, on what, and what the numbers were.
In regulated pharmaceutical manufacturing, COAs are not optional. FDA's current good manufacturing practice regulations at 21 CFR Part 211 require that each batch be tested against written specifications before release and that complete laboratory records be kept. The ICH Q6B guideline lays out the kinds of specifications that apply to peptides and proteins: identity, purity, potency, and limits on impurities and contaminants.
A typical peptide COA reports a few things. Identity is usually confirmed by mass spectrometry, which measures the molecule's weight and checks it against the expected value. Purity is usually measured by HPLC, and is reported as the percentage of the total chromatogram signal that belongs to the main peak. Some COAs add water content, counter-ion content, or a bacterial endotoxin test.
What a COA cannot tell you is the longer list. A purity percentage does not say what the other percent is, or whether it matters. A mass spectrum confirms the main molecule, not the absence of every contaminant. Nothing on the document proves the tested batch is the one in a given container, or that the lab was independent, or that the tests not listed were not simply skipped. And a COA says nothing about whether a substance is approved or safe for human use; the FDA's 2023 review of research peptides such as BPC-157 flagged impurity concerns for exactly that reason.
The limit is that a COA is a lab result, not a regulator's judgment. Inside a licensed manufacturer it sits within a system of inspections. Outside that system, its meaning depends entirely on who produced it. Questions about any actual medication belong with a physician or pharmacist.
Sources
- U.S. Food and Drug Administration, 21 CFR Part 211, Current Good Manufacturing Practice for Finished Pharmaceuticals, sections 211.165 and 211.194
- Code of Federal Regulations 2024
- International Council for Harmonisation, ICH Q6B: Specifications: Test Procedures and Acceptance Criteria for Biotechnological/Biological Products
- ICH 1999
- U.S. Food and Drug Administration, Certain Bulk Drug Substances for Use in Compounding May Present Significant Safety Risks
- FDA.gov 2023
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