Understanding Peptide Purity: HPLC & Mass Spectrometry
Why purity is the most important quality metric for research peptides, and how labs verify it with HPLC and mass spec.
In peptide research, results are only as reliable as the reference material behind them. Purity and correct identity are the foundations of reproducible work. Here is how analytical labs verify both.
Why purity matters
A peptide synthesized in the lab is never perfectly clean straight off the synthesizer - truncated sequences, deletion products, and residual reagents can remain. Purification removes most of these, and purity testing quantifies what is left. Higher purity means fewer confounding variables in research.
HPLC: measuring purity
High-Performance Liquid Chromatography separates the components of a sample as they pass through a column at different rates. The result is a chromatogram with peaks; the area of the main peak relative to the total is reported as a purity percentage. Research-grade peptides are commonly characterized at high purity by HPLC.
Mass spectrometry: confirming identity
Purity alone does not prove you have the right molecule. Mass Spectrometry measures the mass-to-charge ratio of the peptide, confirming its molecular weight matches the expected sequence. Together, HPLC and MS answer two questions: how pure is it, and is it the correct peptide?
Reading a Certificate of Analysis
A Certificate of Analysis (COA) typically lists the peptide name and sequence, the HPLC purity figure with its chromatogram, the MS result, and batch details. When sourcing reference material, COA documentation is a strong signal of a supplier's analytical rigour.
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For research and laboratory use only. Not for human consumption, diagnosis, treatment, or cure of any condition. This article is general reference information and not medical advice.