How to verify a peptide COA (and spot a fake)
A certificate of analysis is only as good as your ability to read it. Plenty of the COAs circulating for research peptides are generic, recycled from an old batch, or simply fabricated. Here's how to tell a real one from a prop — and what a legitimate certificate should actually show you.
When you buy a research peptide, the COA is the document that's supposed to tell you what's in the vial: whether it's the right compound, and how pure it is. The problem is that a PDF or a screenshot is trivial to fake, and a certificate with no verifiable link to the vial in your hand proves nothing. Before you trust any vendor, run their certificate through this checklist.
The 6-point checklist
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The lot number matches your vial
This is the single most important check. The lot (or batch) number printed on the certificate should exactly match the lot printed on the vial you received. A COA is a test of one specific batch — a generic sheet with no lot number, or a lot that doesn't match your label, tells you nothing about what you're holding.
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Purity is shown by HPLC, with a real number
Purity is measured by HPLC (high-performance liquid chromatography) and reported as a percentage — commonly ≥98–99% for research-grade material. Look for an actual figure backed by a chromatogram (the graph of peaks), not just a "passed" or "conforms" stamp with no data behind it.
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Identity is confirmed by mass spec
HPLC tells you how pure; it doesn't tell you the sample is actually the compound you ordered. That's what mass spectrometry (MS) is for — it confirms the molecule's measured mass matches the expected peptide. A complete COA shows both: HPLC for purity, MS for identity. A certificate with only one is telling half the story.
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You can verify it independently
A certificate a vendor DMs you as a JPEG is a claim, not proof — anyone can edit an image. The stronger signal is a COA you can look up yourself by lot number, hosted by the vendor, rather than one that only exists in your inbox.
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The date makes sense
Check the test or issue date. A years-old certificate attached to a compound you bought last week is a red flag — it suggests the COA was recycled from a different batch than the one you received.
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The compound details are correct
The product name, and where shown the molecular formula, molecular weight, and sequence, should match the known values for that peptide. Mismatched or missing identity details are an easy tell that a certificate was copied from elsewhere.
What a real COA actually shows
A legitimate peptide certificate of analysis is a short technical document. Beyond the lot number and dates, you're typically looking at:
An HPLC chromatogram
A graph of one dominant peak (the target compound) with the purity reported as its percentage of the total peak area. A clean, single-peak trace at ≥98–99% is what you want to see; a forest of smaller peaks means impurities.
A mass spectrum
A readout confirming the measured molecular mass matches the theoretical mass of the peptide — this is the identity check. It answers "is this actually the molecule on the label?"
Appearance and physical description
Usually a line noting the material is a white-to-off-white lyophilized powder, which is what most research peptides ship as.
HPLC = how pure. Mass spec = whether it's the right thing. The lot number = whether the certificate is about the vial you actually hold. A real COA answers all three; a fake usually falls down on the third.
Red flags
- No lot number, or a lot that doesn't match the vial.
- A "passed / conforms" stamp with no chromatogram or purity figure behind it.
- Only a JPEG in your DMs, with no way to verify it independently.
- A test date that predates your batch by months or years.
- Purity claims with no HPLC, or identity claims with no mass spec.
- A vendor who gets evasive when you simply ask for the lot-specific certificate.
That last one matters most. Asking for a lot-specific COA is a completely normal request. A vendor who can't or won't produce one has answered your question.
How we handle it
We built our whole process around passing this exact test. Every batch we ship is HPLC-tested, and every certificate is published in a lot-searchable COA library — you can look up the lot printed on your vial and read its certificate yourself, without asking us for anything. That's the difference between "trust us" and "verify it."
Frequently asked
What does a peptide COA actually prove?
It documents testing of a specific batch — its identity (usually by mass spectrometry) and its purity (usually by HPLC). It proves what a particular lot contained when it was tested, which is why the lot number matters more than anything else on the page.
What's the difference between HPLC and mass spec on a COA?
HPLC measures purity — how much of the sample is the target compound versus impurities, as a percentage. Mass spectrometry confirms identity — that the molecule's mass matches the expected peptide. A complete COA shows both.
How do I know a COA isn't recycled from another batch?
Match the lot number on the certificate to the lot on your vial, check the test date is recent, and verify it independently rather than trusting an image. A certificate you can't tie to your specific vial proves nothing about it.
What purity should a research peptide be?
Research-grade peptides are commonly reported at ≥98–99% by HPLC. The number matters less than whether it's backed by an actual chromatogram and a lot-specific certificate you can verify.
See it in practice
Browse our COA library and search any lot number. Every batch, every certificate — verifiable, not just claimed.
Open the COA library