Peptide ChooserHow to read a peptide COA, and what it cannot tell you.
Short answer
A COA is a lab report for one batch. It usually shows how pure the peptide is and whether it is the right one; check whether it also covers the amount, bacterial toxins and germs. It tells you about that batch only, and only if a lab outside the shop did the test. Of the 81 research-use and cosmetic peptide shops we check, 56 posted a report in the last 12 months.1
What is a COA?
A certificate of analysis, or COA, is a short report from a lab that tested a sample of a product. For peptides it is usually one or two pages with the product name, a batch or lot number, the date of the test, the tests that were run and the results.
Shops that sell research-use peptides often post COAs on their product pages. A COA is the closest thing these products have to a quality check, because no approved product exists and no regulator checked the vial.2
Who issues a COA?
There are two kinds. A third-party COA comes from a lab that the shop does not own. A seller COA is made by the shop or by the factory that made the powder. Only the first kind is an outside check.
Look for the lab's name, address and a way to check the report, such as a code or link on the lab's own site. A report with no lab name, or one that names the shop as the lab, tells you only what the shop says about itself.
What does a COA test?
A full report covers five things. Check which of them your report has:
- Purity. How much of the powder is the peptide, shown as a percentage (often measured by HPLC). The rest can be leftovers from making it.
- Identity. Whether the peptide is the one on the label, usually by mass spectrometry: the weight of the molecule found should match the weight expected.
- Quantity. How many milligrams are really in the vial. A pure peptide in a half-full vial is still not what you paid for.
- Endotoxin. Toxins left behind by bacteria.
- Sterility. Whether living germs grew from the sample.
Many peptide COAs show purity and identity only. A report that lists only purity tells you nothing about the amount, toxins or germs.
Why does a COA cover only one batch?
A COA is for the sample the lab received. It is worth something only if the batch or lot number on the report matches the number on your vial. A shop can make a new batch every few weeks; a report from last year says nothing about this month's powder.
Check the date too. A report much older than the product listing, or the same report on several different products, is a warning sign.
What does a good COA look like?
- It names an outside lab, with an address and a way to check the report on the lab's own site.
- It has a batch or lot number that is also printed on the vial.
- It is dated, and the date fits the product you are buying.
- It shows how each result was measured (for example HPLC for purity, mass spectrometry for identity).
- It covers more than purity: the amount in the vial, and for anything injected, endotoxin and sterility.
How often do shops publish them?
Of the 81 research-use and cosmetic peptide shops we check, 56 posted at least one lab report in the last 12 months.1 The rest posted none we could find, or only older ones. In our seller windows this is the "Lab reports" check, and each listing has its own chip: "This product: COA yes" with the number of reports, or "This product: no COA".
A shop with reports is not a shop with good products. It is a shop that shows some of its work.
What can a COA not tell you?
It cannot tell you that a peptide is safe or that it works in people. Only trials can show that, and for research-use peptides there are none that the FDA reviewed.3 It cannot tell you a dose, and we do not either.
Signs that a report needs a closer look: no lab name, no batch number, the same purity to the decimal on every product, a date before the product existed, or a file that looks edited. When in doubt, the lab named on the report can usually confirm whether it issued it.
What to do next
Sources
- Peptide Chooser database: the research-use and cosmetic peptide shops we check, 2 Nov 2026. Their prices and checks are in the seller windows on our goal pages
- Drugs@FDA database (no approved product for retatrutide, PT-141 shop versions, Melanotan II, CJC-1295, ipamorelin or sermorelin on 30 Oct 2026): https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm
- FDA, Development and Approval Process: Drugs: https://www.fda.gov/drugs/development-approval-process-drugs