Reading a Certificate of Analysis
A Certificate of Analysis (CoA) is the document that accompanies a specific lot of a peptide and reports what testing found. It is the single most useful piece of paper for judging whether a research material is what the label claims. Here is how to read one.
Identity: mass spectrometry
Mass spectrometry confirms the molecule's identity by measuring its mass. The observed mass should match the theoretical mass of the intended sequence within a small tolerance. If the measured and expected masses disagree, the vial may not contain the peptide it claims to — no purity figure can rescue a failed identity check.
Purity: HPLC
High-performance liquid chromatography (HPLC) separates the contents of a sample into peaks. The main peak is your target peptide; smaller peaks are related impurities. Purity is reported as the area of the main peak as a percentage of the total. A figure of ≥ 99 % means the target accounts for at least 99 % of the detected material.
Purity tells you how much of the sample is one thing. Identity tells you what that thing is. A trustworthy lot passes both — that is why Pepteed releases against HPLC purity and mass-spec identity together.
Lot number and release date
A CoA is tied to a single production lot, not to a product in general. The lot number on the certificate must match the lot number on your vial. The release date tells you when that lot passed testing — useful context for storage planning.
What a CoA does not tell you
- It is a snapshot at release — it does not certify how the material was stored after it left the lab.
- It does not make any claim about suitability for use in humans or animals.
- It cannot substitute for your own incoming-quality checks if your protocol requires them.
Every Pepteed lot ships with its own CoA showing HPLC purity and mass-spec identity, and the lot number printed on the vial matches the certificate.