Peptide synthesis is not a perfect process. Even under controlled laboratory conditions, the production of a specific amino acid sequence can generate byproducts: truncated sequences, deletion peptides, oxidized variants, and residual synthesis reagents. For research purposes, the presence of these contaminants can compromise experimental outcomes and make results difficult to interpret or reproduce.
High-performance liquid chromatography, or HPLC, is the gold standard for peptide purity analysis. The technique works by separating compounds in a sample based on their chemical properties as they pass through a column under pressure. Each compound travels at a different rate, producing a chromatographic profile where peaks correspond to individual substances. The area under the main peak, expressed as a percentage of total peak area, is the purity figure.
A peptide with 99% HPLC purity means that 99% of the UV-absorbing material in the sample is the target compound. The remaining 1% may include related impurities, though what this represents in practice depends on the synthesis method and purification process used. Mass spectrometry is typically run alongside HPLC to confirm molecular identity by matching the detected mass to the theoretical mass of the target peptide.
At Vanguard Research Labs, every product is accompanied by a Certificate of Analysis generated from third-party laboratory testing. This means the purity figure on the COA was not determined by us but by an independent facility. Batch-level testing is important because peptide quality can vary between production runs. A COA tied to a specific lot number tells a researcher that the material in their hands was specifically characterized, not simply assumed to meet a specification based on earlier testing.
Researchers sourcing peptides for serious investigational work should always request documentation and verify that it applies to their specific batch. The COA should include HPLC chromatograms, mass spec data, and clearly stated purity percentages. These documents are available for all Vanguard products through the COA portal on our website.