How to Read a Peptide Certificate of Analysis (COA)
Updated
A certificate of analysis is the only document that connects a vial to a lab result. Here is what each part means and how to tell a real report from a decorative one.
Batch or lot number
This ties the report to a specific production run. If the number does not match your vial label, the report tells you nothing about what you received.
HPLC purity
High-performance liquid chromatography separates a sample into its components and reports the share that is the target peptide. Research-grade material is commonly offered at 98% or higher. Look at the chromatogram itself, not only the percentage: one dominant peak is what you want to see.
Mass spectrometry (MS)
MS confirms identity by measuring molecular weight. The measured mass should sit very close to the theoretical mass of the peptide. Purity without identity only proves that the vial contains one substance, not that it is the right one.
Lab name, date, and contact details
A trustworthy COA names the testing lab, gives a date, and identifies the analyst or lab contact. If you can contact the lab and confirm the report, that is a strong signal.
Signs a COA may be fake
Identical reports reused across different batches, missing chromatograms, edited-looking fonts, a lab with no online presence, and dates that do not fit the production timeline are all warning signs.
Frequently asked questions
What purity should a research peptide have?
Many reputable suppliers list 98% or higher by HPLC, but purity alone is not enough. You also want mass spec confirmation of identity.
Can I test a peptide myself?
Independent analytical labs will test a sample for a fee. That is the most reliable check if you doubt a supplier's report.
This article is educational and is not medical or legal advice. Peptides discussed are sold for laboratory research use only.