How to read a peptide Certificate of Analysis (COA)
Updated October 2026
A certificate of analysis is the single most important document behind a research peptide. Here's how to actually read one.
HPLC purity
High-performance liquid chromatography (HPLC) separates the contents of a sample and measures what fraction is the target peptide versus impurities. A result like "99.6%" means 99.6% of the material is the intended compound. For research peptides, look for 99%+ and a visible chromatogram.
Identity (mass spectrometry)
Mass spectrometry (often ESI-MS) confirms the molecular weight of the peptide matches its target sequence. A COA should state the expected mass and the observed mass, and they should agree. This is what proves the vial contains the compound on the label, not just something pure.
Net peptide content
Lyophilized peptide also contains counter-ions, water, and salts. Net (or "net peptide") content tells you how much of the vial mass is actually peptide — useful for accurate concentration math.
Endotoxin and sterility
Endotoxin testing (LAL) screens for bacterial contamination byproducts; a low EU/mg figure is good. Together these tests describe how clean the lot is.
Matching the lot
The most important check: the lot number on the COA must match the lot printed on your vial. A certificate for a different batch tells you nothing about what you received. Victory Peps issues a lot-matched COA for every order — request yours from the Quality page.