A Certificate of Analysis is the single most useful document when sourcing research peptides. It tells you what was in the batch, how pure it was, and who tested it. Here is how to read one.
1. Check who did the testing
A credible COA names the laboratory that ran the analysis. Independent third-party labs have no stake in the result, which is why we send every batch outside for testing.
2. Purity by HPLC
High-performance liquid chromatography separates the compounds in a sample. The main peak should dominate the trace; the purity figure is the share of total area under that peak. Research-grade peptides are typically ≥98–99%.
3. Identity by mass spectrometry
Purity alone does not prove you have the right compound. Mass spectrometry (MS or LC-MS) measures molecular mass, which should match the theoretical mass of the target peptide.
4. Match the lot number
The batch or lot number on the certificate should match the number on your vial. A generic COA with no lot number tells you very little.
Red flags
- No laboratory name or contact details
- No lot number or test date
- The same certificate used for every batch
- Purity stated without a chromatogram
You can browse the certificates for every compound we stock in our COA Library.
This article is for educational and laboratory research purposes only. It is not medical advice, and no product mentioned is intended for human use.