How to read an HPLC purity report for a research peptide
A chromatogram looks simple until you ask what the percentage really measures. Here is a practical walk-through for research buyers.
What the percentage means
Reverse-phase HPLC separates a sample by how strongly each component sticks to the column. A detector, usually reading ultraviolet absorbance near 214 to 220 nm where the peptide bond absorbs, draws each component as a peak. Reported purity is the area of the main peak divided by the area of all peaks, so it is a ratio of absorbing material, not a statement about everything in the vial.
What to check on the report
- Lot or batch number that matches the label on your vial.
- Method details: column, gradient, wavelength and run time.
- Retention time and peak shape: one dominant, symmetrical peak.
- Mass confirmation: the observed molecular weight should match the expected value for the sequence.
What it does not tell you
UV detection does not see salts, water or counter-ions, and area percent does not equal net peptide content. That is why identity by mass spectrometry and a documented lot matter as much as the headline number.
Every MPGA Labs batch has a certificate you can open from the COA section of this site. Materials are sold for in-vitro laboratory research only.