Peptide Purity – What It Is & Why It’s Important

Whether for assays, immunization or highly intensive clinical research, peptide purity is a crucial concern in peptide synthesis. What do the differences in purity mean? Is there any benefit to using lower purity peptides? Knowing the answers to these questions will be indispensable to how you gauge the results of your research.

Your Guide to Peptide Purity

Most peptides are purified using high-performance liquid chromatography (or HPLC), in which a peptide-adsorbent material is used to separate the peptide molecules from any impurities. For example, a 50 mg, 99% pure solution of AICAR Ribonuccleotide will contain exactly 49.5 mg AICAR Ribonuccleotide. Exactly 0.5 mg of another material will separate from the solution upon contact with the adsorbent material.

Why Is Peptide Purity Important?

In any area of study, variables ought to be as strictly controlled as possible. If you are researching the effects of AICAR Ribonuccleotide on the endurance of mice, you want to be as confident as you can that it is AICAR Ribonuccleotide and not some extraneous substance that is producing this effect. The higher the purity of your peptides (in many cases), the more accurate your research conclusions will be.

Why Are There Different Peptide Purities?

Many suppliers claim to supply the highest-grade peptides, and indeed Purchase Peptides prides itself on offering only the finest 98.6%+ peptides and research chemicals. Given this fact, why do lower-purity peptides even exist in the first place?

Purity will always guarantee more accurate results. However, there is some research that may also be done using lower-purity peptides and then controlling for them. Thus, your level of purity may depend on what you are using peptides for:


  • Peptide screening
  • Enzyme-linked immunosorbent assays (ELISAs)
  • Some non-quantitative enzyme-substrate studies
  • Phosphorylation reactions
  • Some non-quantitative peptide blocking studies
  • Protein electrophoresis
  • Antigenic determinant mapping


  • Nuclear magnetic resonance (NMR)
  • Semi-quantitative enzymology
  • Biological activity testing
  • Western blotting
  • Cell attachment


  • Quantitative bioassays
  • Quantitative in vitro receptor-ligand interaction studies
  • Biological activity with ligand binding studies
  • Electrophoresis markers and chromatography standards


  • Structure-activity relationship (SAR) studies
  • In vitro bioassays
  • In vivo studies
  • Quantitative studies, including:
    • ELISA
    • Receptor-ligand interactions
    • Peptide blocking
    • Competitive inhibition
    • Phosphorylation
    • Proteolysis
    • Radioimmunoassay


  • Pharmaceutical peptide research
  • Protein crystallography
  • Cosmeceutical peptidess
  • Clinical trials


In cases where extraneous substances closely resemble the peptide in question, researchers may be able to account for their conclusion in light of impurities. However, there are plenty of cases where impurities have completely spoiled research, or even led to toxicity in the test subject. Sub-standard peptide purity may result in shortened or missing sequences of peptides in their naturally occurring state. For this reason, it is always recommended to purchase peptides with as high a purity as possible. Make sure your supplier is accounting for the quality of peptides, for the integrity of your research depends on it.