Mass Spectrometry

Mass spectrometry (MS) ionizes a sample and measures the mass-to-charge ratio of the resulting ions. The observed mass is compared to the theoretical mass of the intended molecule to confirm identity.

For a peptide, MS answers the question “is this actually the sequence it claims to be?” If the measured mass matches the calculated mass for the sequence, identity is confirmed. It complements HPLC, which measures how pure the sample is rather than what it is.