What's Actually in Your Certificate of Analysis?

Reading a COA — And Knowing What to Look For

A Certificate of Analysis (COA) is the document that accompanies every lab-tested compound. It's meant to give you confidence in what you're working with. But not all COAs are created equal — and knowing how to read one is just as important as having one.

What a basic COA includes:

• Compound name and lot/batch number

• Testing method used (e.g., HPLC, LC-MS, NMR)

• Purity percentage

• Date of analysis

• Lab name and signature

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What separates a strong COA from a weak one:

Method transparency. A trustworthy COA tells you exactly which analytical method was used and under what conditions. Vague entries like "tested by HPLC" without chromatogram data attached are a red flag. You should be able to see the raw data, not just the conclusion.

Identity confirmation. Purity alone is not identity. A rigorous COA will include mass spectrometry data confirming the molecular weight of the compound matches the expected value, and ideally NMR data confirming its structure.

Verification capability. Can you independently verify the COA is authentic? At ARS Lab Analytics, every certificate carries a unique task number and verification code that can be confirmed directly through our website — protecting you from counterfeit or altered documentation.

Recency. COAs have a shelf life. Testing performed on a compound six months ago may not reflect its current state, particularly for peptides that are sensitive to storage conditions, temperature, and oxidation. Always check the date.

When evaluating any COA — whether it came from our lab or another — ask yourself: does this document tell me whatthe compound is, how pure it is, how that was determined, and when? If any of those answers are missing, the certificate is incomplete.