How to verify a peptide certificate of analysis

Most people check that a COA exists. Almost nobody checks that it is real. Here is how to do it in about two minutes, with a worked example you can run yourself on one of ours.

A certificate of analysis is only worth what you can verify. A PDF proves nothing on its own — it is an image, and images can be edited. What makes a certificate meaningful is that an independent laboratory will confirm it issued that exact report.

Reputable analytical laboratories know this, which is why most now issue reports carrying a unique verification reference. You give that reference back to the laboratory and it returns the report it holds on file. If the two match, the document is genuine. If they do not, you have learned something far more useful than a purity figure.

The four checks, in order

1. Does the certificate name the laboratory?

“Third-party tested” is not a laboratory. A real report carries the name of the lab that produced it, its contact details, and a task or report number from that lab’s own system. If nobody is named, there is nobody to ask, and the document cannot be verified by anyone.

2. Does the lot number match the vial?

This is the check that catches most bad paperwork. A certificate describing a compound with no batch reference describes nothing in particular — it could relate to any batch, from any year, from any supplier. The lot number is the only thing tying the analytical document to the material in your hand.

Check the number on the certificate against the number printed on the vial you were sent. Not the product name. The lot.

3. Does the verification reference check out?

If the certificate carries a verification key, use it. Enter it on the issuing laboratory’s verification page and compare what comes back against the document you were given: same compound, same batch, same result, same date.

Each key belongs to one report. That is the entire point of it. If you are ever shown two certificates for different compounds carrying the same key, at least one of them has been altered — and the supplier either does not know, which is bad, or does, which is worse.

4. Is the analysis date sensible?

A certificate dated years before the batch was produced is not describing your material. A batch of certificates all sharing an identical analysis date and an identical purity figure to three decimal places is not describing anything at all — real analytical results vary.

Try it on ours

Rather than describe this abstractly, here is a live example you can run in under a minute.

1. Open our certificate library and pick any row — say the DSIP batch, DS10.
2. Note the verification key shown in the table: Q31CH4VZP6DD.
3. Go to janoshik.com/verify and enter it.
4. Compare what Janoshik returns against the certificate we publish. Same task number, same batch, same results.

Do the same with any other row. Every key in that table is different, because every key belongs to one report.

Then do exactly this to any other supplier you are considering. The ones who cannot produce a named laboratory and a checkable reference have told you something.

Three fakes worth recognising

The product-line certificate

A real-looking document with the compound name but no batch number, reused across every order. It is not forged — it simply does not refer to your material. This is the most common by a distance, and the easiest to spot once you know to look at the lot field.

The edited report

A genuine certificate with the compound name, quantity or batch altered. The tell is usually the verification reference: whoever edited the visible fields left the key alone, because changing it would break the only thing they could not fake. Two documents sharing one key is the signature of this.

The unnamed laboratory

Professional-looking layout, plausible chromatogram, no laboratory identified anywhere. Nothing to check, nobody to ask. Treat it as decoration.

What the purity figure does and does not tell you

Once you have established a certificate is genuine, read it properly. Purity by HPLC is reported as area percent of UV-absorbing material — the main peak’s share of what the detector saw, usually at 214 nm. It is a relative measure, not a mass fraction.

A vial can report and still contain counterion, bound water and residual salt alongside the peptide, which is why quantity is a separate result. And purity says nothing about identity: it reports that one peak dominates, not that the peak is the right molecule. That is mass spectrometry, and it is a separate question.

More on this in what purity figures actually measure and how to read a COA.

Why we publish the keys

Publishing verification keys means we cannot quietly revise a result later, and it means any customer, competitor or regulator can check our documents without asking us. That is uncomfortable and it is the point — a claim you can check is worth more than a claim you have to trust.

It also means our own bad results are visible. Where a batch was tested for quantity but not purity, our library says so rather than leaving the column blank. Where a batch did not meet a standard, it is not on sale.