This article supports qualified researchers. It is not medical advice and must not be used to plan human or veterinary administration.
HPLC purity (area%) reports the main peak’s share of UV-absorbing species. Assay / net peptide content estimates how much peptide mass is actually present (accounting for salts, water, etc.). A high HPLC% with a lower assay is common and not automatically a red flag — but a COA with a percentage and no chromatogram is a weaker document.
Prefer COAs that include chromatogram traces and MS identity.
Match lot numbers on the COA to the vial in hand.
Record both purity and identity method in your notebook.
Further study
External links are educational. Prefer institutional and peer-reviewed sources; ignore any “home injection” framing on third-party pages.