Documentation explained
How to read a Certificate of Analysis
A certificate is only useful if you can interpret it. Here is what each section reports — and what it does not.
Lot number
The unique identifier for one production run. A certificate applies to that lot alone — not to the compound generally, and not to any other batch.
HPLC purity
Reverse-phase chromatography separates the target peptide from related impurities. The percentage reports how much of the peptide content is the intended sequence.
Mass spectrometry
Confirms molecular identity by measuring mass. Purity tells you how much; mass spec tells you what. A certificate needs both.
Net peptide content
Lyophilized powder includes counter-ions and residual water. Net peptide content reports the actual peptide mass in the vial, which is lower than gross fill weight.
Endotoxin (LAL)
Screens for bacterial endotoxins, which can confound cell-based assays at concentrations far below anything visible in the material.
Heavy metals
Screens for lead, arsenic, cadmium and mercury carried through from synthesis or handling.
What a certificate does not tell you
A COA describes material at the point of testing. It says nothing about how the vial was stored afterwards, and nothing about lots other than the one named on it. A supplier showing a single certificate for an entire product line is not documenting your material.
Matching a certificate to your vial
Scan the code on your vial. It opens every published certificate for that compound, newest first. Each certificate names the production run it covers — it describes that batch alone, never the compound generally.
