Lab Testing · September 2026
Lab Testing
How to Verify a Peptide Certificate of Analysis — A UK Buyer’s Guide
Almost every UK supplier now shows a certificate. Far fewer show one that names them as the client, references a batch you can match to your vial, and verifies on the testing laboratory’s own system.
Summary
A certificate of analysis is a laboratory’s record of what it found in one sample on one date. It is not a quality guarantee and it does not cover a supplier’s whole catalogue.
The presence of a certificate has stopped being a useful signal, because producing a convincing-looking one costs nothing. What still carries weight is whether the document names an independent laboratory, names the seller as the client, references a batch, and can be checked against the laboratory’s own records.
This is a guide to reading and checking analytical documentation. It is not a purity guarantee, not advice on any particular supplier, and not a statement that any compound is suitable for any use.
What a Certificate of Analysis Actually Is
A certificate of analysis (COA) records the result of testing a specific sample, drawn from a specific batch, on a specific date. It describes that sample. It does not describe every vial a supplier holds, and it does not certify fitness for any purpose.
A useful COA for a research peptide normally carries the compound name and nominal quantity, a lot or batch reference, an HPLC purity result, a mass spectrometry result confirming identity, the date of analysis, the name of the laboratory, and a report identifier allowing the record to be looked up independently.
Remove any of those and the document loses most of its evidential value. A purity percentage with no batch number cannot be tied to the vial in front of you. A report with no identifier cannot be checked against anything.
The Four Checks
| Check | What you are looking for | Why it matters |
|---|---|---|
| Independent laboratory | The report names an outside analytical laboratory, not the seller or an unnamed “partner lab” | In-house testing is not independent. An unnamed laboratory cannot be contacted or checked. |
| Client field | The Client or Customer field names the company you are buying from | A genuine report commissioned by someone else says nothing about this seller’s stock. |
| Batch and date | A lot reference you can match to the vial, and a recent test date | Each production run needs its own test. An old certificate describes material you are not being sold. |
| Portal verification | The report key checks out on the laboratory’s own verification system | A PDF can be edited. The laboratory’s own record cannot. |
Check One — Is an independent laboratory named?
Read the header of the document. It should carry the name of an analytical laboratory that exists independently of the seller. Janoshik Analytical in Prague is the most widely used in this market; there are others.
Phrases such as “tested in our facility”, “verified by our QC team” or “lab tested” with no laboratory named are not independent verification. They may describe real internal testing honestly, but you have no way to confirm any of it.
Check Two — Does the client field name the seller?
This is the check most people skip, and the one that catches the most certificates.
A laboratory report records who commissioned the test. If the Client field names a Chinese manufacturer, a different retailer, or a brand that no longer trades, the document may be entirely genuine — it is simply not about the material this seller is holding. It tells you that a sample somewhere in the supply chain tested well at some point.
This is common enough to have a name: a borrowed certificate. It is not necessarily dishonest, since a supplier may reasonably want to show what their source produces. But it is not the same as having tested their own stock, and it should not be presented as though it is.
Check Three — Is there a batch number, and is the test recent?
Synthesis varies between production runs. A batch that tested at 99.5% tells you nothing reliable about the next batch unless that one was tested too. The batch reference on the certificate should correspond to a reference you can find on the vial, the label or the product page.
If a supplier publishes a single certificate and has been trading for two years, the question worth asking is what happened to the intervening batches.
Check Four — Does it verify at the laboratory?
Janoshik reports carry a unique key and a QR code, and every report in their database can be checked through the Verify function on their own site. Entering the key returns the laboratory’s record directly, rather than the version of the document the seller has chosen to show you.
Compare what the portal returns against the document: compound, quantity, batch, purity figure, mass spectrometry result, date. They should match exactly. A PDF can have numbers altered and a laboratory’s logo pasted onto someone else’s data. The laboratory’s own record cannot.
A Worked Example
Our certificates are published in full on the lab reports page. They are a reasonable set to practise on, because every step below can be run without buying anything.
| Field | Example — KPV 10mg |
|---|---|
| Laboratory | Janoshik Analytical, Prague |
| Client | Pureline Biolabs Ltd |
| Batch reference | PLB-011 |
| Report reference | Task #209945 |
| Date of analysis | 29 July 2026 |
| HPLC purity | 98.015% |
Run the four checks against that row. An independent laboratory is named. The client is the company selling the vial. There is a batch reference and a test date. The report key can be entered at Janoshik’s verification page and compared against the published document.
That certificate sits on the KPV 10mg product page itself, next to the current batch reference, as it does for every compound in the catalogue. You should not have to ask for it.
That figure is 98.015%, not 99.9%. We publish what the laboratory returned. A supplier publishing every certificate in full does not get to choose which results appear — which is precisely what makes the higher figures worth anything.
Red Flags
| Pattern | What you will see |
|---|---|
| Self-issued | The seller’s own template and branding, no external laboratory named. Often a suspiciously round 100.00% or 99.99%. |
| Borrowed | A genuine laboratory report whose Client field names a different company. |
| Fabricated | Formatting that does not match the laboratory’s standard layout, a missing report key, or a verification link that does not resolve. |
| Stale | A real, verifiable report a year or more old, with no newer batches published. |
| On request | No published certificate at all — only an offer to send one after payment. |
| Partial | A cropped image showing the purity line only, with client, batch and report key removed. |
What a Verified Certificate Still Does Not Tell You
It is worth being straightforward about the limits, because a verified COA is necessary evidence rather than sufficient evidence.
- It describes a sample, not every vial. The laboratory tested what it was sent, and a certificate is only as representative as the sampling behind it.
- It covers one batch. It says nothing about the batch before or after unless those were tested and published too.
- HPLC purity is not net peptide content. Area-percent does not account for salts, residual solvent, water or counterions.
- It says nothing about handling after testing. Storage temperature, transport and elapsed time all matter, and none of them appear on a certificate.
A supplier who publishes verifiable certificates and is candid about these limits is giving you more useful information than one advertising guaranteed purity with nothing behind it.
Common Questions
How long should verification take?
Under a minute once you know where to look. Find the report key on the document, enter it on the laboratory’s verification page, and compare the returned record against the document you were shown.
Is a supplier without published certificates automatically suspect?
Not automatically, but you are being asked to take the quality claim on trust. Independent testing is an ordinary cost of supplying research materials, and publishing the result is the cheapest part of it.
What if the purity figure is lower than a competitor’s?
A verifiable 98% is stronger evidence than an unverifiable 99.9%. The second figure has no laboratory standing behind it, and nothing prevents a seller printing whatever number they prefer.
Can a QR code on a vial be trusted?
A QR code is only as good as where it points. If it resolves to the laboratory’s own verification record, that is meaningful. If it resolves to an image hosted on the seller’s website, you are back to trusting the seller.
Does a certificate prove a compound is safe or approved?
No. Analytical testing can support identity and purity claims. It does not create a marketing authorisation, and it says nothing about suitability for human use.
Should every batch have its own certificate?
Yes. Testing is per batch because synthesis varies between runs. A supplier testing one batch a year is not testing the material you are being sent.
References
- Janoshik Analytical. Analytical testing services and report verification.
- Pureline Biolabs. Published batch certificates.
- Medicines and Healthcare products Regulatory Agency. Borderline products: how to tell if your product is a medicine.
Last reviewed September 2026. Questions or factual corrections: contact Pureline Biolabs.
Chris Harris
Co-director of Pureline Biolabs Ltd. Commissions the independent batch testing with Janoshik Analytical, reviews every certificate before stock is listed, and publishes all of them in full. Registered in England and Wales, Company No. 17236739.
All products supplied by Pureline Biolabs Ltd are intended solely for in vitro laboratory research purposes. They are not medicines, not approved for human or veterinary use, and not for human consumption. Pureline Biolabs Ltd · Company No. 17236739 · purelinebiolabs.com