How Research Peptides Are Tested: HPLC & Mass Spectrometry

Reversed-phase HPLC — measuring purity

High-performance liquid chromatography separates the components of a sample as they travel through a column at different speeds. In reversed-phase HPLC (the common mode for peptides), the main peptide and its impurities elute at different times, producing a chromatogram of peaks. Purity is reported as the area of the main peak as a percentage of all peaks — so a single tall, clean peak indicates high purity, while extra peaks indicate impurities.

Mass spectrometry — confirming identity

A mass spectrometer ionises the molecule and measures its mass-to-charge ratio, giving a precise molecular mass. By comparing the detected mass with the expected mass for the target peptide, identity can be confirmed. This is the check that the right molecule was synthesised — HPLC alone cannot tell you that.

Why both are needed

Purity and identity answer different questions. HPLC tells you how much of the main component is present; MS tells you what that component is. A batch documented with HPLC purity AND LC-MS identity (expected vs detected mass) has been checked on both axes; one without the other is only half-characterised.

Independent vs in-house testing

Testing can be done in-house by the manufacturer or by an independent third-party analytical lab. Independent testing reduces the conflict of interest in a supplier certifying its own material. The certificate should state who performed the analysis and when.

How Index Peptides applies this

Published batch records are linked from the product page, and any batch can be checked by lot number on the verify page. Where no report is published, no purity or identity result is claimed.

Frequently asked questions