Verifying a peptide means answering two questions: is it really the correct compound? and how pure is it? Two complementary techniques are used for this.

High-performance liquid chromatography (HPLC) separates the components of a sample by passing it through a column. Each component exits at a different time and generates a peak; the area of the main peak, as a percentage of the total, is the purity measure. A result of ≥99% indicates that almost all of the material is the target compound.

Mass spectrometry (MS) ionizes the sample and measures the mass of its molecules. By comparing the measured mass to the theoretical mass of the peptide, it confirms identity. HPLC tells how much; MS tells what. Together they give a verifiable picture of a lot.