How to Read a Certificate of Analysis (No Science Degree Needed)
The Journal · 7 minute read
A Certificate of Analysis (COA) is the most important document in peptide research — and almost no one teaches beginners how to read one. It answers two questions.
1. Is it the right compound?
Identity is confirmed by mass spectrometry. The measured mass should match the known molecular weight of the named peptide.
2. How pure is it?
Purity is measured by HPLC and given as a percentage. Research-grade material is typically 98% or higher, and the chromatogram should show one dominant, clean peak.
What to check, line by line
Batch / lot number — it must match the vial you are looking at. A COA for a different batch tells you nothing about yours.
Purity figure — look for ≈98%+ with a clean single peak.
Identity — the mass-spec result should match the compound's molecular weight.
Test date and lab — recent, and ideally an independent third-party laboratory.
Sterility / endotoxin results where applicable.
Red flags
No COA available at all.
A "COA" that is just a marketing graphic with no actual chromatogram.
No batch number, or a batch that does not match.
Purity well below ~98% with no explanation.
An old test date with no recent verification.
The mindset: a label is a claim; a COA is evidence. Learning to read one turns you from a hopeful buyer into an informed researcher.
For educational and research purposes only. This content is not medical advice. Compounds referenced are research use only and not intended to diagnose, treat, cure, or prevent any disease. Free Peptide University does not sell compounds.