Field guide

COA Reader.

How to read a peptide certificate of analysis: every field, what the numbers mean, and the red flags that signal a fake.

What is a peptide COA?

A certificate of analysis is a batch-specific document summarizing the analytical results for a particular peptide lot. It’s what connects a physical vial to its identity, purity, content, and contaminant profile: the four things worth knowing before trusting a research peptide.

A good COA answers four questions: Identity (is this the right sequence?), Purity (how chemically clean is it?), Content (how much actual peptide?), and Contaminants (any harmful compounds present?).

Field-by-field breakdown

COA verification checklist

Open the COA you’re checking and tap what it actually shows on both lists below. This runs entirely in your browser: nothing you tick is sent anywhere.

Red flags

Each red flag = risk.

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Green flags

Each green flag = trust.

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Cross-check with verified lab reports

Instead of judging a COA image in isolation, cross-check it against reports already on file from suppliers with a live, verifiable test on record.

Browse lab reports

Bottom line

HPLC tells you how clean it is. MS tells you what it is. Net content tells you how much. Contaminant tests tell you it’s safe to handle. A complete COA touches all four.

A COA is a research documentation tool, not a medical certificate or a guarantee. Pair it with your own judgment and quality checks rather than treating it as a substitute for either.

Questions

Frequently asked questions.

What should a complete COA contain?

The product and its batch or lot number, a named analytical method with real parameters, the actual result rather than only a summary figure, the testing laboratory's identity, an analyst or QA sign-off, and a date. Missing any of these weakens what the document can tell you.

What is the difference between third-party and in-house testing?

Third-party testing is performed by a laboratory independent of the seller; in-house QA is the seller testing their own product. Both can be legitimate, but independent testing carries more weight, and a document does not always make the distinction obvious.

Why does a chromatogram matter?

A chromatogram or mass spectrum lets a reader check the stated purity against the underlying trace. A typed percentage with nothing behind it is the weakest form of evidence a certificate can offer, because there is no way to verify where the number came from.

What are the clearest warning signs?

No lot number anywhere; no analytical method named; no chromatogram or spectrum; the same certificate reused across different products or batches; dates that do not line up with when the product was listed; stripped PDF metadata; and no laboratory or analyst identified.

Does this tool store the COA I am checking?

No. The checklist runs entirely in your browser and nothing you tick is sent anywhere. It is a reading aid, not an upload or verification service.