What HPLC measures
Reverse-phase high-performance liquid chromatography (RP-HPLC) separates a sample's components based on how they interact with a stationary phase as they're carried through a column, allowing purity to be measured as a percentage of the target compound relative to synthesis byproducts and degradation products. It's the standard method for quantifying research peptide purity, and it's what the purity percentage on any legitimate COA is actually based on.
Why HPLC alone isn't enough
HPLC tells you how pure a sample is, but not definitively what it is — a highly pure sample of the wrong sequence will still show a high HPLC purity result. That's why every lot we test also goes through mass-spectrometry sequence confirmation (ESI-MS), which verifies molecular identity independently of the purity measurement. A COA showing only an HPLC result without accompanying identity confirmation is incomplete documentation.
How results are reported
Our COAs report the HPLC method used, the purity result as a percentage, and the test date, alongside the mass-spec confirmation for that same lot. This is the same format across every compound in our catalog, from BPC-157 to Tirzepatide.