Stable isotope labelling is a chemical reagent in which the molecules of a compound contain one or more stable isotope atoms and are analysed and determined using their unique tracer properties.

Stable isotope labelling techniques are based on the principle of labelling a reactant by replacing specific atoms with an isotope, which then causes the reactant to undergo a reaction and detects the atoms with a change in neutron number, which can be tracked by reactions, metabolic pathways or cells. Stable isotope (13C, 15N, 13C15N) labelled peptides are commonly used as ‘chemical tags’ in quantitative proteomics for the detection and tracing of biological samples. Quantitative proteomics methods mainly use high-resolution mass spectrometry to separate isotope-labelled and non-labelled peptide ions or peptide ions, and use the intensity values of their detected signals for quantitative calculations.

Stable isotope labelling technology has the advantages of high sensitivity, simple positioning and accurate quantification, which makes isotope modification get more and more widespread attention in the field of medicine and biochemistry.