How to Read a Peptide Certificate of Analysis (COA)

What a COA is

A Certificate of Analysis (COA) is a lab report for a specific batch of a compound. A real one is tied to a batch number and comes from a third-party testing lab — not just the seller's word. It's the single most useful document for judging a research peptide before you buy.

HPLC — the purity number

HPLC (high-performance liquid chromatography) separates the sample and reports purity as a percentage. For research peptides you generally want to see ≥98–99%. The chromatogram should show one dominant peak; a forest of smaller peaks means impurities.

Mass spectrometry — the identity check

Mass spec (MS) confirms the compound is actually what the label says by measuring its molecular weight. The measured mass should match the known molecular weight of the peptide. This is how you know a vial labeled "tirzepatide" contains tirzepatide.

Red flags

Walk away from: no COA at all; a COA with no batch number; the same generic "stock" COA reused for every product; purity below the mid-90s; or a seller who gets defensive when you ask. Any of these is a sign of the underdosing that plagues the gray market.

The bottom line

A source that tests is a source worth using. Every lot we carry has a COA available on request — just ask on our Telegram channel or at 561-591-9642 and we'll send what we have for the compound you're looking at.