HPLC measures purity
Reverse-phase HPLC (RP-HPLC) separates the components of a sample by hydrophobicity. The detector counts how much of the eluted material is the target peptide vs. impurities. Purity is reported as a percentage of total peak area.
- Industry minimum: >=98% by area
- Research grade: >=99%
- Pharmaceutical grade: >=99.5% with specific impurity profiles
HPLC tells you nothing about what the molecule actually is — only what fraction of the sample is the major peak.
Mass spectrometry verifies identity
ESI-MS measures the mass-to-charge ratio of ionized molecules. A peptide theoretical mass is calculable from its sequence. The observed mass should match within +/-1 Da.
A common failure mode: HPLC shows 99.5% purity, but the major peak is not actually the target peptide. Without MS confirmation, you cannot tell.
What a complete report shows
- HPLC chromatogram with purity percentage and method (column, gradient, detector wavelength)
- MS spectrum with observed mass, theoretical mass, and the matching adduct ion
- Both done on the same lot, on the same or sequential days
What we publish
Every Peptech batch ships with HPLC + MS in a single COA. We do not release a batch with one but not the other.