How to Read a Peptide Certificate of Analysis (COA)
A plain-language walkthrough of HPLC purity, identity tests, batch numbers, and red flags on research peptide COAs.
A Certificate of Analysis is the primary quality document for research materials. Treat it as batch-specific data, not a brand brochure.
Purity (HPLC) is usually reported as a percentage of the main peak. Higher is better for many applications, but identity confirmation (mass spectrometry) matters as much as a headline purity number.
Match the batch number on the COA to the label on the vial. If they do not match, do not use the material in critical work until resolved.
Red flags include missing lab names, impossible purity (100.00% with no method), recycled COAs across unrelated products, and documents that cannot be verified with the vendor.
Purity North lists batch purity on Lab Results and supports batch lookup on the COA Verify page for every research peptide SKU.