Lab results · Method guide
How to read a peptide certificate of analysis
A certificate of analysis (CoA) is a laboratory report of the tests run on one batch of material. Reading one properly takes five checks: that the batch number matches the vial, who tested it and when, what the HPLC purity figure actually measures, whether identity was confirmed by mass spectrometry, and which tests are absent.
1.Match the certificate to the batch
A certificate of analysis (CoA) describes one manufactured batch, so the first check is that the batch or lot number on the certificate matches the number on the vial label. A certificate for a different batch of the same compound says nothing about the material in hand, because purity and content vary from one synthesis run to the next.
2.Check the testing laboratory and date
The issuing laboratory, its contact details and the test date should all be printed on the certificate. An independent third-party laboratory is a stronger source than the seller's own testing. Where the laboratory offers an online verification code or lookup, use it to confirm that the certificate was issued as shown and has not been edited.
3.Read the HPLC purity figure correctly
HPLC purity is the percentage of the detected UV signal that belongs to the main peptide peak. A result of 99% means 99% of what the detector saw at that wavelength eluted as the target peak. It is a relative figure: it does not state how much peptide is in the vial, and impurities that do not absorb at the detection wavelength are not counted.
4.Look for identity confirmation
Purity and identity are different questions. HPLC shows that one component dominates the sample; mass spectrometry (MS or LC-MS) confirms that the dominant component has the expected molecular mass. A certificate that reports HPLC purity without a mass result shows the sample is pure, not that it is the named compound.
5.Note what the certificate does not test
A purity certificate only documents the tests printed on it. Endotoxin (bacterial lipopolysaccharide, usually measured by LAL assay), sterility, heavy metals, residual solvents and net peptide content are separate analyses. If a test is not on the certificate, the certificate is silent about it rather than showing a pass.
Where to see real certificates
Every certificate Veridian Research has published is listed in the certificate library, and the results are collected in one table on the purity data page. Terms used here are defined in the glossary.
Last reviewed 2026-10-01. For laboratory research use only.