How to read a peptide COA
A Certificate of Analysis is the single most important document a vendor can show you. Here is how to read one in two minutes, and how to tell a real one from wallpaper.
A COA (Certificate of Analysis) is a lab report for one specific batch of one specific product. It states what the sample was, who tested it, how they tested it, and what they found. A good COA is checkable: you can contact the lab and confirm it is real. A bad COA is a decoration: a PDF with a purity number on it that nobody can verify.
The five fields that actually matter
- The lab’s identity. A real COA names the laboratory, and that lab has a real website, a real address, and a way to contact them. “Tested by our quality department” is not a lab.
- The batch or lot number. The COA must reference the exact lot printed on the vial you would receive. A COA without a lot number proves nothing about your order.
- The test date. Peptide batches turn over. A COA from years ago tells you about a product that probably no longer exists in stock.
- The method. For purity you want to see HPLC (high performance liquid chromatography), and for identity you want mass spectrometry (MS) confirming the molecular weight matches the peptide named on the label. Purity without identity is half an answer: 99% pure could mean 99% pure something else.
- The actual numbers. Real results are specific, like 98.7%. Be suspicious of round, perfect claims repeated across every product.
How to verify a COA in five minutes
- Look up the lab. Real website, real location, working contact. Search the lab name plus “reviews” or “verification”.
- Email or call the lab and ask them to confirm the report number. Legitimate labs answer this question every day.
- Match the lot number on the COA to the lot on the product page or vial.
- Check the date against the batch you would actually buy.
- Compare COAs across the vendor’s products. Identical layouts are normal; identical numbers are not.
In-house results are not the same thing
Some vendors publish in-house test results. That is better than nothing, but it is the company grading its own homework. Independent third-party testing removes the conflict of interest, which is why it is the single most heavily weighted criterion in our methodology.