What a COA actually is.
A Certificate of Analysis, or COA, is a lab report on one specific batch of a compound. A vendor sends a sample to a testing lab, the lab runs it, and the result is a one-page document that says what the sample is, how pure it is, and when it was tested. It is the difference between a vendor telling you a vial is 99% pure and a vendor showing you that it is.
Two things make a COA worth trusting: it comes from an independent third-party lab, not the vendor's own equipment, and it is tied to a specific batch you can match to the vial in your hand. A purity number with no document behind it is a marketing claim, not data.
The fields that matter.
Most COAs share the same handful of fields. These are the ones to read first:
| Field | What it tells you |
|---|---|
| Compound / product | The peptide the lab believes it tested. It should match exactly what you are buying. |
| Purity (HPLC) | What percentage of the sample is the target compound. For research peptides, the common range you will see is roughly 98 to 99.9 percent. |
| Identity (LC-MS or MS) | Mass spectrometry confirming the sample actually IS that peptide, by its molecular weight. Purity without identity is half the picture. |
| Batch or lot number | The code that ties this report to a specific production run. This must match the code on your vial. |
| Test date | When the sample was analyzed. A recent date matters more than an old one, because it reflects the batches a vendor is shipping now. |
| Testing lab | The lab that ran it. Independent third-party names are what you want to see. |
On the COAs we link across the site, the labs that show up most are Janoshik, Kovera Labs, MDx BioAnalytical, and Freedom Diagnostics. Janoshik in particular is the lab the research community leans on, on the strength of its turnaround and blind-testing approach, even though it is not ISO 17025 accredited. Accreditation is a useful signal, but in this market a named third-party report beats an unnamed in-house one every time.
Identity is not the same as purity.
These two get conflated, and it matters. Identity answers "is this the right molecule?" It is usually confirmed by mass spectrometry, which weighs the molecule and checks it against the known mass of the peptide. Purity answers "how much of the sample is that molecule, and how much is something else?" It is measured by HPLC, which separates the sample into peaks and reports the target peak as a percentage of the total.
You want both. A sample can be the correct peptide but only 90 percent pure, which means a tenth of what you bought is byproducts or fragments. A sample can also report a high purity number for the wrong compound entirely if no one ran an identity test. A complete COA shows the peptide name, an identity confirmation, and an HPLC purity figure together.
How to confirm the COA is actually yours.
A real COA for someone else's batch does you no good. When your order arrives, spend thirty seconds doing this:
- Find the batch or lot code printed on the vial label.
- Pull up the COA the vendor publishes for that product.
- Confirm the batch code on the document matches the code on your vial. If it does not match, the published purity does not describe what you are holding.
- Check the compound name and the test date while you are there.
This is the whole reason we link the actual per-batch certificate on each product page rather than a general claim. You can open the document, read the purity for yourself, and see the batch it belongs to.
The red flags.
Most of the bad signal in this market is easy to spot once you know what to look for:
- In-house testing only. If the vendor is its own lab and there is no independent third party named, the number is unverified.
- No batch code. A COA you cannot tie to a specific vial is decoration.
- A general lab-results page instead of a per-batch report. A page that says "we test everything" is not the same as the certificate for your batch.
- A purity claim with no document at all. A vendor that posts a number but no certificate is asking you to trust the number. We never do that, and you should not either.
- Stale dates, or the same COA reused across every product. One certificate cannot cover many different batches.
- Edited or low-resolution images. Real reports have a lab header, a date, and often a verification code or QR. Photoshopped COAs are a known problem in this space.
A high purity number tells you the sample is mostly the right compound. It does not tell you the product is sterile, correctly dosed in the vial, or safe for any particular use. Purity is one piece of the picture, not a safety guarantee. Everything on this site is for research use only.
Frequently asked.
What is a COA for peptides?
A Certificate of Analysis is a third-party lab report on a specific batch of a peptide. It states the compound, its purity (usually by HPLC), often an identity confirmation (by mass spectrometry), the batch code, the test date, and the lab that ran it.
What does HPLC purity mean?
HPLC, or high performance liquid chromatography, separates a sample into its components and reports the target compound as a percentage of the total. A 99 percent HPLC purity means about 99 percent of the sample is the intended peptide and the rest is byproducts or related fragments.
Is Janoshik a legit lab?
Janoshik is the testing lab most trusted in the research-peptide community, valued for its turnaround and blind-testing approach. It is not ISO 17025 accredited, which is worth knowing, but a named Janoshik report is far stronger evidence than an unnamed in-house test. Kovera Labs, MDx BioAnalytical, and Freedom Diagnostics also appear on COAs we link.
How do I know a COA matches my vial?
Match the batch or lot code. Find the code printed on your vial label and confirm it appears on the certificate. If the codes do not match, the report describes a different batch and its purity number does not apply to your product.
What purity should I look for?
For research peptides, certificates commonly land in the 98 to 99.9 percent range. Higher is better, but a real per-batch report at 98.5 percent is more meaningful than an unverifiable 99.9 percent claim with no document. Always weigh the number against whether you can actually see and verify the certificate.