How to read a certificate of analysis (COA)
What each part of a peptide lab report means and what to check before trusting it.
A certificate of analysis is a lab's report on one tested sample. For peptides the useful parts are:
- Identity, usually by mass spectrometry (MS): is the molecule the one on the label?
- Purity, usually by HPLC, as a percentage: how much of what's in the vial is the target peptide rather than fragments or by-products.
- Quantity (also called content or assay): how many milligrams were actually measured, compared with the label. A 10 mg vial measuring 8.1 mg is 81% of label.
- Lab, date, batch or lot number, and ideally a way to verify the report on the lab's own website.
Red flags worth taking seriously: the report is made out to a different brand; the same lot number appears on unrelated products; the date is in the future; the report can't be verified with the lab; or it shows a different compound than the product. On this site, vendors whose reports show those signs get a COA concerns badge, and vendors caught faking reports are banned.
Remember a COA shows one sample the vendor chose to test and publish. Independent testing of vials bought anonymously, like Finnrick's, is stronger evidence.
- Check identity, purity and quantity separately.
- Verify the report with the lab when possible.
- A COA describes one sample, not every batch.
Quick check
Purity says how clean the contents are; quantity says how much is there. This vial is clean but holds only 79% of the label.
A report issued to another company is often borrowed from someone else's test.
Vendor lab reports and bans · Testing labs
General education, not medical advice. Nothing here recommends using any compound or amount.