Certificate of
Analysis library.

What a peptide certificate of analysis is

A peptide certificate of analysis is a laboratory report on one specific batch. It records the lot number, the purity measured by RP-HPLC, the identity confirmed by mass spectrometry, and the laboratory that performed the work. It describes that batch only — which is why the lot number on the report has to match the number printed on the vial.

The purity figure is an area percentage: of everything the detector registered, that proportion was the target peptide. It does not account for water, salts or counter-ions, which are real mass in the vial and invisible to the detector. Net peptide content, reported separately on these certificates, is the figure that answers how much of the vial is peptide.

Every certificate below was produced by an independent laboratory and published before the lot was offered for sale. How to read one, line by line.