Plain-words guide
How to read a peptide COA (lab report)
A COA, or certificate of analysis, is the piece of paper that says what is actually in a vial. Sellers wave the word around; few make the paper easy to check. Here is how to read one in five minutes, and the tricks to watch for.
What a COA is
When a batch of peptide is made, a sample can be sent to a testing lab. The lab measures what the sample is and how pure it is, then writes a report: the certificate of analysis. One batch, one report. If a seller tests their products, this paper exists. If you cannot see it, you are taking their word.
The five things to find on the report
- The lab's name. A real report says who ran the test, at the top, with a logo and usually an address. "Third-party tested" with no lab name is a claim, not a report. You should be able to find the lab's own website.
- The batch or lot number. The report covers one batch. Match the number on the report to the number on the vial you receive. A report with no batch number, or one that does not match your vial, tells you nothing about your vial.
- What was tested. Look for two different things: identity (is this substance what the label says, usually by mass spectrometry) and purity (how much of the sample is that substance, usually by HPLC, shown as a percentage). A report with only one of the two is half a report.
- The date. Reports are dated. A three-year-old report cannot cover this year's batches. Recent inventory should have recent reports.
- The numbers themselves. A purity percentage on the report beats one in the marketing copy. If the homepage says one number and the report says another, believe the report.
Watch for these patterns
- Report on request only. "Email us for the COA" means you cannot check before you pay.
- A screenshot in a tab. An image pasted into the product page is harder to read, save, and verify than a real PDF, and easier to edit.
- The nameless lab. "Independently tested by a third-party laboratory" without a name cannot be checked. You cannot look up the lab's accreditation or scope.
- The recycled report. One old report used for every batch of a product. Check the batch number and the date.
- Marketing math. A "99.9% pure" badge with no report behind it is a design choice, not a measurement.
The one-line test: can you, before paying, open a dated report from a named lab whose batch number you can match to the vial that will arrive? If yes, the seller is showing their work. If no, they are asking for trust they have not earned yet.
Try it on real sellers
Our seller table runs exactly this check on ten US peptide sellers, cell by cell, with the date we looked and a link to what we found. It re-runs when pages change.
What this guide does not cover
Whether any peptide is right for you, how much to use, or how to prepare it. Those are not paperwork questions; they belong with a licensed doctor. This site's methods page explains where we draw that line and why.
See which sellers pass the paper test.
Open the seller table