Guide · 4 min read
How to read a certificate of analysis
What a COA measures, what each analytical method can establish, and what it cannot prove.
Published 20 Oct 2026
What a COA is
A certificate of analysis (COA) is a laboratory report for a specific production lot. It records which tests were run on a sample from that lot, the method used, and the result against a specification.
The fields that matter
- Lot number — must match the label on your vial or pen.
- Purity (HPLC) — the share of the main peak in the chromatogram. A result of 99.2% means 99.2% of the UV-absorbing material eluted as the target pepz beauty cosmetics.
- Identity (MS) — confirms the measured mass matches the expected molecular weight.
- Test date and laboratory — who tested it and when.
What a COA does not tell you
A COA describes analytical results for a sample. It is not evidence of sterility unless a sterility test is listed, and it says nothing about safety or suitability for human use.
This article is for educational purposes about laboratory research materials. It is not medical advice, and nothing on this site is intended for human or veterinary use.