LC-MS identity check for a peptide lot

LC-MS means liquid chromatography coupled to mass spectrometry. The chromatograph separates the sample, and the spectrometer reports a mass for a selected peak, often as a mass-to-charge ratio that the laboratory converts to an observed molecular mass. Laboratories compare that observed mass with the mass calculated from the amino-acid sequence, including common terminal modifications when the report states them. Agreement supports identity. It does not replace the area percent, and the area percent does not replace it.

A file that shows only a chromatogram is not an LC-MS identity package, even if the filename says MS. Open the PDF and find the mass. The method note is HPLC versus LC-MS. Third-party files linked from this catalog are usually Janoshik reports tied to one lot.