- Janoshik Analytical is an independent Czech laboratory that tests samples anyone sends it. Its reports carry a key you can verify on janoshik.com — do that before you trust one.
- A report describes the sample that was posted, not the vial in your hand. Batch traceability — carton, certificate, report — is what closes that gap.
- Two labs will not report the same purity for one batch. A gap of a few tenths of a percent is normal; a gap of several points is a question.
- No purity report covers sterility, endotoxin, heavy metals or fill volume. Ask what else was tested.
Search for any research peptide vendor in the UK and the word "Janoshik" appears within a scroll. It has become shorthand for "tested" — which is a problem, because a Janoshik report is a specific document that proves specific things, and the shorthand has drifted well past them. This is what the report is, how to check one, and where its edges are.
Who Janoshik is
Janoshik Analytical is an independent analytical laboratory in the Czech Republic. It accepts samples by post from anyone — vendors, manufacturers, individual buyers — runs a defined set of tests, and returns a report. Because it is unconnected to any manufacturer or vendor and because it will test a sample from a member of the public, it has become the de-facto third-party lab for the peptide market in Europe and beyond.
That independence is real and it is the whole point. It is also the source of the report's main limitation, which we'll come to.
What the report measures
A standard Janoshik peptide report gives you:
- Identity — the measured molecular mass, by mass spectrometry, against the theoretical mass of the named compound. This is the check that the peptide is what the label says.
- Purity — by HPLC, as a percentage of chromatogram area belonging to the main peak. What that number does and doesn't mean.
- Quantity — for solutions, a concentration in mg/ml; for lyophilised material, a mass per vial against the label claim. This is the field that catches under-filling, and it is the one a manufacturer's certificate most often lacks.
Each report carries a task number and a verification key. Enter the key at janoshik.com/verify and the lab's own site confirms the report is genuine and shows you its contents. A vendor who publishes a Janoshik result without the key is asking you to take a screenshot on trust; a vendor who publishes the key is inviting you to check. Check.
The customer-submission problem
Because anyone can send Janoshik anything, a report only ever describes the sample that was posted. It cannot know whether that sample came from the batch on the shelf, from a hand-picked vial, or from a different supplier altogether. This is not a flaw in the lab; it is the nature of a service that tests what it receives.
The answer is traceability, and it is the vendor's job, not the lab's: the report should name a batch, the carton in your hand should carry the same batch number, and the vendor's testing page should tie the two together so that the chain is visible. Without that chain a Janoshik report is a true statement about an unknown object.
Two labs, two numbers — why
Here is a real example from our own range, as of the report date. For the current batch of Retatrutide 40 mg the manufacturer's HPLC-MS certificate reads 99.3%. Janoshik's independent report on a pen from the same batch, analysed on 28 August 2026, reads 98.86%. For the current Tirzepatide 40 mg batch the figures are 99.3% and 99.59% — the independent number this time higher.
Neither lab is wrong. Purity by HPLC depends on the column, the gradient, the detector wavelength, how the software integrates the baseline and which small peaks it counts — and on how much time has passed since manufacture, because a solution in a pen is slowly changing from the day it's filled. Two competent laboratories running two validated methods on two dates will land within a few tenths of a percent of each other, and that is what you see above.
What you want from the pair is agreement in kind: the identity confirmed, the purity in the same band, the quantity consistent with the label. A gap of half a point is the method. A gap of five points — or a certificate that says 99% where an independent report says 80% — is the product.
The four things no purity report tells you
A Janoshik peptide report is an identity, purity and quantity document. It is not, and does not claim to be, a safety document. Four things fall outside it:
| Not covered | What it would take | Why it matters |
|---|---|---|
| Sterility | Microbiological testing of the filled product | Whether anything is growing in the solution |
| Endotoxin | A separate LAL assay | Bacterial residues that survive filtration |
| Heavy metals | ICP-MS | Contamination from synthesis or handling |
| Fill volume | Gravimetric check of the finished unit | Whether the pen contains what the label says, independent of concentration |
A manufacturer operating a proper quality system tests these at release. A vendor who re-labels bulk material of unknown origin does not, and a purity report cannot reveal the difference. Which is why a Janoshik result is best read alongside a manufacturer's certificate, not instead of one — the two documents answer different questions.
What to check, in order
- Is there a key? Verify it on janoshik.com. No key, no report.
- Does the report name a batch, and does it match your carton?
- Does the identity (mass) match the compound? This is the field that catches a mislabelled vial.
- Does the quantity match the label? This is the field that catches an under-filled one.
- Is the purity in the same band as the manufacturer's certificate? Agreement in kind, not to the decimal.
- What else was tested at release? Sterility, endotoxin, metals — ask.
How Biovanta uses it
Every Biovanta batch is HPLC-MS quality-controlled by the manufacturer in Switzerland, and the certificate is available before you order. Independently of that, we submit pens from each batch to Janoshik as they come on sale and publish the result — task number, batch, figures and verification key — on the testing page, next to the manufacturer's number, so the two can be read together. Where a batch's report hasn't come back yet, that page says so rather than implying it has. Products are supplied strictly for in-vitro laboratory research.
Sources
Questions this article answers
Is Janoshik an independent laboratory?
Yes. Janoshik Analytical is a Czech analytical laboratory unconnected to any manufacturer or vendor. It tests samples posted to it by anyone, and each report carries a verification key that can be checked on the lab's own website.
How do I verify a Janoshik report?
Take the verification key printed on the report or published by the vendor and enter it at janoshik.com/verify. The lab's site confirms whether the report is genuine and shows what it contains. A result published without a key can't be verified.
Why does the Janoshik purity differ from the manufacturer's certificate?
Purity by HPLC depends on the method — column, gradient, wavelength, baseline integration — and on how long after manufacture the sample was run. Two competent labs typically land within a few tenths of a percent of each other. A large gap, not a small one, is the warning sign.
Does a Janoshik report prove a peptide is safe?
No. It confirms identity, purity and quantity of the sample submitted. It does not test sterility, endotoxin, heavy metals or fill volume, and it describes the sample that was posted rather than the vial you receive — which is why batch traceability and a manufacturer's certificate matter alongside it.
Want the certificate for a real batch?
Name a compound and we'll send the manufacturer's HPLC-MS certificate for the batch you would receive — before you order, no account needed.