Bridge Labs
High-performance liquid chromatography (HPLC) separates the components of a sample so the main compound can be distinguished from related substances — synthesis by-products, truncated sequences and degradation products. The result is an objective, quantitative picture of how much of the sample is the intended compound.
What it measures
A purity test answers a narrow but important question: of everything the method can detect in this sample, what proportion is the target compound? This is reported as a percentage purity for the main peak, alongside the related substances seen with it. The figure is an area-percent value, and it reflects what the detector can see — some salts, counter-ions or residual water may not be captured by a UV purity figure.
Typical approach
For peptides, purity is commonly assessed by reversed-phase HPLC (RP-HPLC). The sample is injected onto a hydrophobic column; a water/organic gradient passes through; components separate by how strongly they interact with the column, leaving at different retention times; and a UV (often diode-array) detector records each as it elutes, producing a chromatogram.
How to read a result
Read the headline main-peak area-percent together with the chromatogram and the related substances — several small impurities tell a different story from one large co-eluting peak at the same overall purity. Purity is not identity, content or sterility; those are separate, complementary tests.
To arrange testing, see submit a sample.