Almost every vendor in this market publishes a certificate of analysis. Most of those certificates are worth nothing. Here is how to read one properly, and what separates a document that proves something from a picture of a document.
There is an uncomfortable fact underneath the research-peptide trade: the barrier to entry is a website and a supplier contact, and the one thing a buyer cannot check by looking is the only thing that matters. A vial of white powder looks identical whether it is 99% pure or 40% pure with the balance made up of truncated sequences, residual solvent and mannitol. The certificate of analysis exists to close that gap. It closes it only if the certificate is real.
What a COA actually is
A certificate of analysis is a laboratory's report on a specific batch of material. Not on the product line, not on the compound in general — on the batch. It should tell you four things: which compound was tested, which batch it came from, what methods were used, and what the results were.
Two analytical methods carry the weight.
HPLC — high-performance liquid chromatography — separates everything in the sample by how strongly it sticks to a column as solvent pushes it through. The output is a chromatogram: a flat baseline with peaks rising out of it, one peak per compound. Purity is the area of the target peak as a percentage of the total peak area. A 99% result means the target peptide accounts for 99% of what the detector saw.
Mass spectrometry ionises the sample and measures mass-to-charge ratios. It answers a different question: not how pure, but what is it. A peptide has a molecular weight determined by its amino acid sequence, and MS confirms the material matches that weight.
You need both, and this is the part people miss. HPLC alone tells you the sample is 99% one thing. It does not tell you that thing is the peptide you ordered. A vendor could supply 99% pure mannitol and produce a beautiful chromatogram. Only mass spectrometry closes that loop.
The batch number is the whole game
If you take one thing from this article, take this: a certificate without a batch number that matches the number printed on your vial tells you nothing about your material.
This is the most common form of dishonesty in the market, and it is not even technically a lie. A vendor sends one genuine batch for testing, gets a genuine 99% certificate back, and then publishes that certificate alongside every subsequent batch for the next two years. Every word on the document is true. It describes material you do not have.
Check the batch number on your vial against the batch number on the report. If they do not match, the report is decoration. If your vial has no batch number at all, you have no way to connect it to any testing whatsoever, and that alone should end the conversation.
Reading the chromatogram
Most forged certificates fall apart in the chromatogram, because faking a convincing trace is harder than editing a number.
A real chromatogram has a flat, slightly noisy baseline. Analytical instruments produce noise; a perfectly smooth line is a drawing, not a measurement. It has one dominant peak for the target and usually a handful of small ones — solvent front, minor impurities, truncated sequences from incomplete synthesis. A trace showing a single peak and absolutely nothing else is suspicious rather than impressive.
Peak shape matters too. A genuine peptide peak is roughly symmetrical, sometimes with mild tailing. Peaks that are perfect isosceles triangles have been drawn. And the numbers should be internally consistent: if the report claims 99.2%, the visible impurity peaks should plausibly account for the remaining 0.8%. When the stated purity and the visible trace disagree, one of them is fiction.
Then check the metadata. Real reports carry a date, an instrument or method identifier, an operator or laboratory reference, and a retention time for the main peak. Forgeries tend to be light on all four, because each one is a detail that can be checked.
Does the laboratory exist?
A surprising number of certificates name laboratories that cannot be found. Search the name. A genuine analytical laboratory has a website, a physical address and a way to contact it. Some will confirm whether a report number is theirs if you ask — and a vendor who becomes evasive when you say you would like to verify the report with the issuing lab has answered your question.
Be wary, too, of a report that names no laboratory at all, or that carries only a logo and no contact details. The whole point of third-party testing is that a third party staked its name on the result. A report that names nobody has no third party in it.
Why vendors cut this corner
It helps to understand the economics, because they explain the behaviour.
Independent HPLC and MS testing on a single batch costs somewhere in the region of €80 to €200 depending on the laboratory and the turnaround. For a vendor buying a ten-vial kit at €60 wholesale, testing every batch of every product is a significant fraction of margin — and it is a cost the customer cannot see and mostly does not ask about. The incentive to test one batch, publish that certificate forever and pocket the difference is strong, and the chance of being caught is small.
This is also why the batch-number check is so effective. It is the one question that costs a dishonest vendor real money to answer honestly.
What you can reasonably ask for
None of this requires you to become an analytical chemist. Four questions get you most of the way:
- Can I see the COA for the batch I would actually receive? Not a sample report, not the product page image — the current batch.
- Does it include mass spec, or only HPLC? If only HPLC, you know purity but not identity.
- Which laboratory issued it, and can I verify it with them?
- Will the batch number on the vial match the report?
A vendor who answers all four without friction is probably doing the work. One who deflects, sends a report with the batch number cropped out, or explains why verification is not possible has told you what you needed to know.
Our own reports are on the lab reports page, and you can request the certificate for a specific batch by email before you order. More on how we handle batch testing is on the lab reports page.
All products are supplied strictly for in-vitro laboratory research use. Not for human or veterinary use.