How to read a peptide COA: the fields that matter, and the ones that give a fake away

A certificate of analysis is a report issued by a laboratory that tested a sample from one production lot.

It answers two questions about that lot only: is it the compound named on the label? (identity) and how much of what is in the vial is that compound? (purity).

The word batch matters. A peptide is made in lots; each lot is a separate synthesis and a separate purification.

A certificate describes the lot it was drawn from and no other. A supplier that shows one certificate for a compound, year after year, is showing a document, not a test.

In this market the reference laboratory is Janoshik Analytical, an independent lab whose reports carry a test number that anyone can look up at verify.janoshik.com.

Other labs exist; what they have in common, when they are worth anything, is that the report can be checked at the source.

Read a COA top to bottom. Every line below should be present; a missing line is a question the supplier did not want asked.

Laboratory and test number

The lab's name, address and a unique test or task number. The number is the whole point: it is what you type into the lab's verification page. A certificate with a logo but no number cannot be verified.

Sample description and lot number

The compound name, the stated quantity (for example "GHK-Cu, 100 mg") and the lot number.

That lot number comes with the task number and verification key, which the laboratory confirms on its own site. A certificate the laboratory cannot confirm describes no batch you can trace.

Purity: HPLC

Purity is measured by reverse-phase HPLC with UV detection: the figure is the area of the main peak divided by the total area of all peaks.

Some laboratories also print the chromatogram, the column and the gradient; that is an option, not a requirement. What matters is a measured percentage tied to a test number the laboratory confirms.

What that percentage does and does not say is explained in HPLC purity: what 99 % means.

Identity and quantity: what is in the vial

HPLC says how pure; it does not say pure what. The report must name the compound the laboratory found and give the quantity measured in mg against the quantity on the label. Some laboratories add a mass spectrum as an option.

Date

The date the sample was analyzed.

A lot sells through in weeks to months; a certificate dated a year ago describes material that is most likely gone. A recent date, with a lot number, is the sign that the certificate describes stock that is still on sale.

Photo of the tested vial

Serious labs photograph the vial as received.

A photo of a vial wearing the supplier's own label proves the supplier sent its finished product for testing. A photo of a bare vial, or no photo at all, means the sample came from somewhere else in the chain.

Further reading: storage and shelf life and the COA of a water lot.

There are two kinds of certificate in circulation, and they do not carry the same weight.

• Manufacturer COA. Issued to the factory that synthesized the bulk peptide, often in-house, sometimes by a third party. It describes the bulk material before it was shipped, divided, re-bottled and re-labeled by whoever sells it to you. It is also the certificate most often copied and re-used by resellers who never tested anything.
• Supplier-branded COA. The supplier labels its own vials, sends one from each lot to an independent lab, and publishes the report with the photo of that labeled vial. This certificate covers the object you actually receive.

A supplier who only shows a manufacturer's certificate is telling you it did not pay to test its own product. Testing costs a few hundred dollars per lot; that cost is what a research supplier's margin is for.

1. Find the test number on the certificate (Janoshik prints it as a task ID at the top of the report).
2. Open the lab's verification page (for Janoshik, verify.janoshik.com) and enter the number, or follow the link the supplier gives on the product page.
3. Compare what the lab shows with the PDF the supplier published: compound, quantity, lot, purity figure, date, photo. They must match line for line.
4. Check that the lot number on the lab's copy is the one on the supplier's certificate.

If the number returns nothing, or returns a report for a different compound or quantity, stop there. The supplier's PDF has been edited, and every other claim on the site inherits that fact.

Further reading: verify a Janoshik report in 3 steps.

Fakes are usually lazy. The common tells:

• Mixed typefaces. One number in a slightly different font, weight or baseline than the text around it: the edited field.
• A test number that returns nothing on the lab's site, or returns a different sample.
• Dates that do not line up. A test date after the "published" date, or a certificate that predates the supplier's existence.
• A bare vial, or no photo. The sample was not the supplier's finished product.
• Round numbers everywhere. Real measurements read 99.13 %, not 99 %; a report full of round figures was typed, not measured.
• One certificate for every size. A 5 mg vial and a 10 mg vial come from different fills; each has its own lot.
• Purity without supporting lab data, or data with the axes cropped off.

The product pages of the OXpeptides catalog link their Janoshik report where one is published (the Retatrutide and GHK-Cu pages); the supplier checks that go with it are in how to check a peptide supplier and where to buy research peptides in Europe, and the worked example for one compound is in the GHK-Cu buying guide.

Further reading: suppliers scored on their COAs.