Mass spectrometry (MS) measures the mass-to-charge ratio of molecules with high precision. For a peptide reference material it answers the identity question: is this the right molecule?
Expected vs. observed mass
Every peptide sequence has a calculable theoretical mass. MS reports the observed mass of the sample. When the observed value matches the expected value within instrument tolerance, identity is confirmed.
Why it complements HPLC
HPLC can show that a sample is a single, clean compound — but not which compound. MS supplies that missing piece by pinning down the molecular mass. Together they form the backbone of a credible COA.
What a mismatch means
If observed mass departs from expected mass beyond tolerance, the material may be a different sequence, a modified form, or a mixture. A trustworthy supplier will not release such a batch as the labelled product.
Reading it on the certificate
Look for both the theoretical mass and the found mass, ideally with the ionisation method noted. Traceable instrument detail is a sign of genuine third-party analysis.
Research use only.