How the method works
In reversed-phase high-performance liquid chromatography, a dissolved sample is pushed through a column packed with a water-repelling material. Different molecules travel through the column at different speeds, so they leave at different times.
A detector records each component as a peak. The result is a chromatogram: a chart of peaks over time.
How purity is reported
Area purity compares the area of the main peak with the total area of all detected peaks. A result such as 98.4% means the main peak made up that share of what the detector saw under those conditions.
Limits to keep in mind
- It only reflects components the detector can see under the chosen conditions.
- It does not measure how much peptide is in a vial.
- It does not test for sterility, endotoxins, or heavy metals.
- It is usually paired with an identity method, because a pure peak could still be the wrong compound.