What is COA? (Peptide Glossary)
COA: Certificate of Analysis. A laboratory document verifying a product's identity, purity, and contaminants - the single most important quality document in the research peptide market.
A Certificate of Analysis is the lab report that accompanies a batch of peptide. A legitimate COA shows at minimum: the compound name, batch or lot number, HPLC purity percentage, and mass spectrometry confirmation of molecular weight. Better COAs also include endotoxin levels, residual solvent analysis, water content, and the name of the laboratory that performed the testing.
The critical distinction is first-party versus third-party COAs. A first-party COA comes from the lab that made or sells the peptide - it proves little, because the seller is grading their own homework. A third-party COA comes from an independent laboratory with no financial relationship to the vendor. When we score suppliers, third-party batch-specific COAs are the single largest factor.
Watch for COA red flags: the same PDF reused across every product, no batch number, no lab name, blurry screenshots instead of downloadable documents, or purity claims without a chromatogram. Some vendors have been caught photoshopping COAs or buying fake ones. When in doubt, contact the testing lab named on the COA and ask them to confirm the batch number - legitimate labs will verify.
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