Academy · Beginner
Understanding Certificates of Analysis (COAs)
How to read a peptide COA: purity by HPLC, identity by mass spec, batch codes, retention time and the signature block.
What a COA contains
A real COA is a one or two page PDF issued by the testing lab. It names the compound, lists the batch code, shows the HPLC chromatogram with the main peak, reports purity as a percentage of total area, shows the mass-spec spectrum confirming the molecular weight, and ends with the lab's signature and date.
How to read it
Match the batch code on the PDF to the batch code printed on your vial. Confirm the molecular weight on the mass-spec page matches the theoretical weight for that peptide. Look at the chromatogram — there should be one dominant peak with minor noise, not multiple competing peaks.
Red flags
No batch code. No lab name or signature. 'Purity report' that is actually just a screenshot. Chromatogram missing entirely. Purity reported without HPLC method. Same COA reused across multiple batches.
Frequently asked questions
Who should issue a peptide COA?+
An independent third-party analytical lab, such as Janoshik Analytical. Look for the unedited lab-issued PDF, not a supplier-made summary.
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