What Is a Certificate of Analysis (COA) for Peptides?
A Certificate of Analysis (COA) is a laboratory document that confirms a peptide's identity, purity, and contaminant status. Here is what it shows and how to read one.
A Certificate of Analysis, commonly shortened to COA, is the most important document any research peptide vendor can provide. It is a laboratory-issued report that confirms the identity, purity, and contaminant status of a specific batch of peptide.
What a real COA contains
A legitimate COA from a third-party analytical lab will name the testing laboratory, identify the compound by molecular weight and CAS number, report a purity percentage (typically by High Performance Liquid Chromatography), and date the test. Premium COAs also include endotoxin testing (USP 85), sterility testing (USP 71), and elemental impurity panels (USP 232).
Why COAs matter for research peptides
Research peptides are not produced under FDA-regulated manufacturing conditions. The only buyer-facing verification of what is actually in a vial is the COA. Without a COA from a named, verifiable third-party lab, the buyer has no independent confirmation of what they received.
How to verify a COA is real
Several analytical labs (Janoshik, Freedom Diagnostics, Bioviridian, ILS Laboratories, Accumark) offer public verification portals. Where a lab offers one, the COA carries a unique key or accession number that can be entered on the lab's website to confirm the document was actually issued by that lab. If the COA does not name the lab, no verification is possible.
Red flags on a COA
Common signs a COA cannot be trusted: the testing laboratory is not named, the sample name does not match the product label, there is no verification key, the test date is more than 12 months old, or the purity is reported as a vague "greater than 99 percent" with no decimal precision.
Frequently Asked Questions
Do all peptide vendors provide a COA?
No. Many vendors either provide no COA, provide a self-issued document that is not third-party verified, or use unnamed laboratories. Peptide Source Review audits every vendor for COA evidence quality.
Can I get a COA after I purchase?
Yes. Most legitimate vendors will email a COA on request after purchase. If a vendor refuses to provide one or says "COA available on request" but never delivers, treat that as a red flag.
What does the purity number on a COA mean?
The purity percentage is the chromatographic area percentage of the target compound compared to all other detected peaks in a High Performance Liquid Chromatography (HPLC) run. It does not measure identity, endotoxin, or sterility on its own.