Reading a peptide COA: six checks

A certificate of analysis (COA) is a lab’s report on one sample. On research-peptide sites it is often the only quality evidence offered, so it is worth reading closely.

1. Is it tied to a lot?

The COA should carry a lot or batch number that matches the product. Some vendors publish a table of lots with dates — for example, one seller in our directory lists compound, lot, manufacturer code, date, purity and laboratory for each certificate.

2. Who tested it, and when?

Look for the laboratory’s name and a test date. Then check that the lab exists and, if it offers one, use its verification system. Vendors in our directory name labs such as Vanguard Laboratory, Chromate, Kovera, BioRegen and Freedom Diagnostics Testing.

3. What does the HPLC number mean?

HPLC purity is the share of the detected signal in the main peak. A 99% figure says little if the main peak is the wrong molecule.

4. Is identity confirmed?

Identity needs mass spectrometry. A matching molecular weight — PubChem lists, for example, 1419.5 g/mol for BPC-157 — is the minimum.

5. Were contaminants tested?

Endotoxin, sterility and heavy-metal tests are separate from purity. Several vendors mention them; check that the COA actually reports them.

6. Does the amount match?

Some labs report net peptide content (mg per vial). That is different from purity and matters if you are doing reconstitution arithmetic.

Our 2026 vendor transparency report records which vendors publish which of these items.