Published by Peptide Protocols · Reviewed September 2026 · How we make these pages · Educational & research purposes only — not medical advice.
A COA — Certificate of Analysis — is the lab report that tells you what's actually in a vial. In a gray market full of mislabeled and under-dosed products, it's the single most important thing to check. But most people don't know how to read one. Here's the plain-English decoder.
The COA is the centerpiece, but it's part of a bigger vetting process — reputation, labeling, storage, shipping. Our complete supplier checklist walks through all of it, so you can vet any vendor with confidence.
See the full supplier checklist →People obsess over which peptide to research and skip the question that actually determines safety: is this vial what the label says? A verified, high-purity product with a matching COA is the foundation everything else builds on. Get this right and you've eliminated the biggest risk in the whole space. (More in peptide safety basics.)
We do not recommend or partner with any peptide supplier. Use the checklist instead: third-party COAs that match your batch and lot, stated purity, clear research-use labeling, real support and proper cold-chain shipping.
The supplier checklist →Educational content only. Confirm the legal status where you live before ordering anything.
Look for ≥98% by HPLC. Lower (or unstated) purity is a red flag.
Then it doesn't tell you anything about what you received. The lot on the COA must match the lot on your vial — otherwise treat it as no COA.
No — a decorative certificate is marketing. A real COA shows actual lab data (HPLC chromatogram, mass spec, purity %, lot number).
Our guides pair the how-to with the sourcing know-how — plus the Universal Excel Logbook that does the reconstitution math for 38+ peptides.
Browse the full library on Etsy →The one formula, a BAC-water chart, and the 10 most-researched beginner peptides — the math done for you. Print it for the fridge.
🎁 Send me the free cheat sheet →