Peptide Purity: HPLC and LC-MS Explained Simply

Two analytical methods answer the key quality questions about a peptide batch: "Is it the right molecule?" and "How pure is it?" Here's what the values mean.

Why Purity Matters in Research

In laboratory research, Reproducibility crucial. An impure or incorrectly identified substance can falsify results without it being immediately obvious. Therefore, each batch is analytically characterised before use – documented in Certificate of Analysis (COA).

HPLC – the purity

HPLC stands for High-Performance Liquid Chromatography. Simplified: The sample is passed through a separation column in which the individual components move at different speeds. The result is a Chromatogram with signal peaks. The large main peak is the target molecule; small side peaks are impurities. The area ratio gives the Purity percentage – for example, "≥ 99%".

LC-MS – the identity

LC-MS couples liquid chromatography with a mass spectrometer. The mass spectrometer determines the Molecular weight very precise. If the measured mass matches the theoretically expected mass of the peptide, then the Identity is confirmed: it is indeed the declared substance and not something else.

How to read "≥ 99% purity"

• The value refers to the tested batch – not a blanket.
• "≥ 99%" means that at least 99% of the detected components are the target molecule.
• The statement is only meaningful in conjunction with the identity confirmation for LC-MS – a high purity value for the wrong substance is worthless.

What the values don't say

Purity and identity are analytical quality characteristics. They make no statement regarding suitability for human or animal use, efficacy, or safety. All products are intended solely for scientific in-vitro laboratory research (Research Use Only).