How to Read a Certificate of Analysis (COA)
4 min read
A COA is your proof of identity and purity. Here's what each part means and what to look for.
What a COA proves
A Certificate of Analysis is a third-party lab report verifying two things: identity (the vial contains the compound on the label) and purity (how much of the sample is that compound vs. byproducts).
Reputable research suppliers make a batch-specific COA available. A generic or missing COA is a red flag.
The two tests that matter
HPLC (High-Performance Liquid Chromatography) separates the sample into its components and reports purity as a percentage — look for 98–99%+.
Mass Spectrometry (MS) confirms the molecular weight matches the expected peptide, proving identity. The best COAs include both.
What to check
Batch/lot number that matches your vial, a recent test date, the testing lab's name, and a purity figure. We make ours available on request via the Lab Tests page.