Educational content only.
Short answer: HPLC estimates how pure a sample is. Mass spectrometry confirms that the main substance is the compound it claims to be. You want both.
HPLC (high-performance liquid chromatography)
A liquid carrying the sample is pushed through a column. Different substances move at different speeds, so they separate. A detector draws a graph with peaks. The size of the main peak compared with the others gives a purity percentage.
Mass spectrometry (MS)
MS measures the molecular weight of the molecules in a sample. If the measured weight matches the expected weight of the peptide, that supports its identity.
Why both matter
- HPLC alone says how much of the sample is one substance, but not what that substance is.
- MS alone says what the main molecule is, but not how pure the sample is.
What a good report looks like
- A chromatogram graph, not just a number
- The main peak clearly labeled
- A measured mass close to the theoretical mass
- Lab name, date and batch number
Limits
These tests don’t automatically show sterility, endotoxins, heavy metals or whether your vial came from the tested batch. Some vendors test for these separately.
Bottom line
Learn to read the graph, not just the percentage.