A Certificate of Analysis is only worth something if it's genuine. Because CoAs are just PDFs, a convincing-looking one is trivial to fake, copy from another batch, or lift from a different supplier entirely. Most buyers have never been shown what to actually check, so a professional layout and a lab logo is enough to pass. Here are the five things to look at before you trust one.
Every genuine CoA is tied to one specific production batch. The batch or lot number printed on the certificate should match the number printed on the vial in your hand — not a similar one, the same one. A certificate with no batch number at all, or one that doesn't match, isn't telling you anything about what you actually received.
The strongest CoAs can be checked outside the PDF itself — a report number, QR code or verification key that lets you confirm the result on the testing lab's own website. If a certificate offers no way to verify it beyond "trust the document", that's the single biggest tell. Anyone can put a lab's name on a PDF; not everyone can fake a working verification lookup.
Purity (usually HPLC) and identity (usually mass spec / LC-MS) are two different tests answering two different questions. Purity tells you the sample is clean. Identity confirms it's actually the compound claimed — by molecular weight, not just by the label. A CoA that only shows a purity percentage, with no identity confirmation, is only half a test. See our guide to reading a CoA for what each section should contain.
Check that the dose stated on the certificate matches the dose printed on the vial label — a 10mg CoA attached to a 20mg vial (or vice versa) is a mismatch that shouldn't happen with genuine, batch-specific documentation. This is an easy thing to miss when a certificate "looks right" at a glance.
A genuine certificate states which lab performed the testing and the method used (e.g. "RP-HPLC, C18 column, detection at 214nm"). If the lab isn't named, or the method is vague ("tested for purity" with no detail), there's no way to independently assess the result — or follow up with the lab directly.
Why this matters more than it seems
A supplier that publishes real, verifiable CoAs has nothing to gain from a buyer checking closely. A supplier whose "certificates" don't survive that check is relying on you not looking. Five minutes comparing the batch number on your vial against the one on the certificate, and testing the verification link if one exists, tells you which kind of supplier you're dealing with.
See real, verifiable examples
Every batch we sell has its real Certificate of Analysis published in our CoA Library — batch number, purity result, identity confirmation and lab verification details, all matching what's on the vial you receive. Compare a few against the checklist above to see what a complete, genuine CoA actually looks like.
Related reading
How to read a Certificate of Analysis · Peptide purity testing: HPLC & mass-spec · Testing & quality
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