Glossary
Certificate of Analysis (COA)
A COA is the batch-specific test report for a peptide: HPLC purity, MS identity, appearance and test date. The items a complete certificate has to include.
A certificate of analysis documents the testing carried out on one specific batch of material. It is neither advertising nor a generic product sheet: it states what was measured on a single, identified lot, with which method and on what date. Without a lot number, a certificate cannot be matched to the vial on your bench and is, in practice, impossible to verify.
Contents of a complete COA
- Product name and the complete sequence, with modifications such as amidation noted
- Lot number, date of manufacture or testing, and amount per vial
- HPLC purity expressed as area percent, stating method and detection wavelength, with the chromatogram attached
- Identity by mass spectrometry: theoretical mass, measured mass and ionisation technique
- Appearance and, if determined, water content, counter-ion or net peptide content
- Name of the testing laboratory and an authorising signature
How to use it
Most of the information sits in two values: identity shows you have the correct molecule, and purity tells you how much other material is present alongside it. Neither means much alone, and neither can be carried over from one lot to another. Independent third-party testing adds confidence because whoever reports the result is not the one selling the product.
Related terms
Read how to read a peptide COA and third-party testing explained.