Mass spectrometry confirms a peptide's identity by measuring its molecular weight and comparing it to the expected value for the intended sequence. This guide explains the method and why it matters.
What mass spectrometry measures
A mass spectrometer ionizes the peptide and measures its mass-to-charge ratio, from which the molecular weight is determined. That measured mass is the molecule's fingerprint.
Confirming identity
Each peptide sequence has a precise theoretical molecular weight. If the observed mass matches the expected mass within a small tolerance, the material is confirmed as the intended molecule.
What a mismatch indicates
A measured mass that differs from the expected value signals a different or modified molecule, which is why this check is essential before relying on a reference compound.
Why it complements HPLC
HPLC reports how much of the sample is the main component; mass spectrometry confirms that component is the right molecule. Purity and identity are different questions, and a complete COA answers both.
Find a COA: search every third-party lab report by product or batch number in our certificate of analysis library.
Related research guides
Research-use note
All materials discussed are supplied for in vitro laboratory research use only.
