HPLC vs. Mass Spectrometry: What Purity and Identity Data Mean
Purity and identity answer two different questions. Here is how HPLC and mass spectrometry each contribute to a complete quality picture.
Two numbers dominate a peptide COA, and they are often confused. HPLC tells you how pure a sample is; mass spectrometry tells you what the main component is. You want both.
What HPLC measures
High-performance liquid chromatography separates the components of a sample over time. Integrating the resulting peaks gives a purity figure as an area percentage. It is excellent at flagging related impurities and truncated sequences, but on its own it cannot prove the main peak is the intended molecule.
What mass spectrometry measures
Mass spectrometry ionizes the sample and measures mass-to-charge ratios. A match between the observed mass and the theoretical mass of the target sequence confirms identity. MS answers the question HPLC cannot: is this actually the peptide on the label?
Why the combination matters
- HPLC alone: pure — but pure what?
- MS alone: correct molecule — but how much else is in the vial?
- HPLC + MS: a defensible picture of both purity and identity.
A strong COA reports both, from a reproducible method. As always, this material is intended for analytical and laboratory research only.
Further reading
- High-performance liquid chromatography — how purity is separated and measured.
- Mass spectrometry — how identity is confirmed by mass.
Research use only - not for human or veterinary use. Nothing here is medical advice.