Isotope labelling

Introducing selected isotopes into molecules to support detection or assignment. In nuclear magnetic resonance, labelling can add observable spins or suppress unwanted relaxation pathways.

Isotopic labelling of selected methyl groups to provide sensitive NMR probes in a relatively sparse spin network.

Replacement of hydrogen with deuterium. In protein NMR, suitable deuteration reduces proton dipolar relaxation but also removes directly observable proton signals unless selected sites are retained or reintroduced.