Encyclopedia entry

HPLC purity

HPLC (High-Performance Liquid Chromatography) is a lab technique that separates the components of a sample by chemical property (typically polarity or hydrophobicity) and reads the relative proportion of each. For peptides, "99% HPLC purity" means the named peptide accounts for at least 99 percent of the total peptide content of the sample. It is the standard purity claim for research peptide retailers.

What HPLC proves

• · The proportion of the named molecule in the sample (relative to other detectable peptide content).
• · The absence of major synthesis by-products at the stated purity threshold.
• · Repeatability when the same sample is tested again.

What HPLC does not prove

• · Biological activity. A 99% pure dead peptide is still 99% pure.
• · Sterility. Sterility is a separate analytical test, often using direct culture or rapid microbial detection.
• · Correct labelled dose. Dose accuracy requires a separate quantitative analytical test, not just purity percentage.
• · Endotoxin content. Endotoxin testing uses LAL or recombinant Factor C, not HPLC.
• · The molecule is what the label says it is, on its own. HPLC tells you the proportions; mass spectrometry confirms the identity by molecular mass.

Mass spectrometry as the sister test

Mass spectrometry (MS) measures the mass-to-charge ratio of a molecule, which lets a lab confirm the identity of the named peptide. A Certificate of Analysis that pairs HPLC purity with MS identity is meaningfully stronger than HPLC alone. UK retailers including my-peptides and Nooku tend to publish both; others publish HPLC only.

Related: Certificate of Analysis · UK research peptide retailers.