How Peptide Purity Is Measured
Peptide purity is normally measured by reversed-phase HPLC with UV detection. The area of the target peak is expressed as a percentage of the total detected peak area. The figure is a relative chromatographic measure of peptide-related species and does not describe total vial contents, sterility or identity.
Published 2026-08-22 · Updated 2026-08-22 · Reviewed by the Lana editorial team
What does the percentage actually represent?
An HPLC purity result of, for example, 98% means the target peak accounts for 98% of the detected absorbance area under the stated method conditions. Substances that do not absorb at the detection wavelength or do not elute under the method may not be represented at all.
Why is method context important?
Purity results depend on column chemistry, gradient, wavelength and run time. Two laboratories can report different purity values for the same material using different methods, which is why reports should state the method used.
What purity does not establish
Purity does not establish that the peak is the intended compound (that requires mass spectrometry or another identity method), how much peptide is in the vial (that requires quantitative analysis), or that the material is sterile or endotoxin-free.