The integrity of peptide research depends entirely on the quality of the compounds being studied. A peptide described as "99% pure" tells only part of the story. Understanding what that figure represents — and what analytical methods produced it — is essential for any serious researcher.
What HPLC Purity Means
High-Performance Liquid Chromatography (HPLC) is the gold standard analytical method for determining peptide purity. The technique separates components of a mixture based on their differential interaction with a stationary phase, generating a chromatogram where each compound appears as a peak proportional to its concentration.
A purity figure of ≥99% by HPLC indicates that 99% or more of the UV-absorbing material in the sample elutes at the correct retention time for the target peptide. This figure does not, by itself, confirm identity — only that the predominant species is consistent with the expected compound.
Mass Spectrometry Confirmation
For rigorous research applications, HPLC purity should always be accompanied by mass spectrometry (MS) confirmation. MS analysis determines the molecular weight of the predominant species in the sample, providing direct evidence of chemical identity. Researchers should verify that the observed mass matches the theoretical molecular weight of the target peptide within accepted tolerances (typically ±1 Da).
What a CoA Should Include
A credible Certificate of Analysis for a research peptide should document:
Why Source Matters
Research conducted with substandard peptides produces unreliable data. Impurities may exert biological effects in cell culture or animal model systems that confound results and lead to erroneous conclusions. This is particularly important when working with novel compounds where the literature base is limited.
Sourcing peptides from suppliers who provide comprehensive, third-party CoA documentation is not merely good practice — it is a prerequisite for publishable research.
All peptides discussed in this article are intended exclusively for laboratory research. Not for human use.