Research basics • May 20, 2026

Peptide COA Basics

COA basics for peptide research readers: lot numbers, purity, identity testing, dates, lab details, and common red flags.

Educational disclaimer: This page is for research literacy only. It is not medical advice, dosing guidance, sourcing advice, a protocol, or a recommendation to buy or use any compound. Affiliate disclosure: we may earn a commission from links on this site, at no extra cost to you.
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What a COA should identify

A useful certificate of analysis should connect to a specific lot or batch and show the reported test date, method, lab identity, and analyte.

A generic PDF without lot matching is weaker than a document that can be tied to the exact material being evaluated.

Purity and identity are different

Purity percentages and identity confirmation answer different questions. HPLC may show a peak pattern, while mass-based methods can support identity checks.

A high purity number alone does not prove complete documentation quality.

Watch for red flags

Old dates, missing lot numbers, unclear lab contact information, recycled PDFs, and claims that exceed the method are reasons to slow down.

COAs are due-diligence documents, not safety guarantees or use instructions.

HPLC vs LC-MSCompare methods →Lot numbersMatch documents →COA checklistUse the checklist →

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