COA
LC-MS on a peptide COA
Liquid chromatography–mass spectrometry reports an observed mass (or ion) for a species in the run. On this sector’s certificates it is used as identity support, not as a second purity percentage.
What this tells you
- Whether a mass consistent with the expected sequence (and charge state) was detected.
- Sometimes, whether obvious mass-shifted impurities are visible in the spectrum — if the spectrum is published.
What this does not tell you
- How pure the sample is. A correct mass on a 60% area peak is still a correct mass.
- Sequence confirmation of isobaric impurities.
- Net peptide content.