Isotopic Labelling

An isotope (an atom with a detectable variation in neutron count) can be tracked as it moves through a reaction, metabolic pathway, or cell using the technique known as isotopic labelling (or isotopic labelling). By substituting certain atoms with their isotopes, the reactant is "labeled." The reaction is then allowed to happen on the reactant. The sequence the isotopic atom followed in the reaction or the metabolic pathway of the cell is determined by measuring the position of the isotopes in the products. Stable nuclides or radionuclides can be used for isotopic labeling. The labelling in the latter scenario is known as radiolabeling. There are several ways to detect the presence of labelling isotopes in isotopic labeling, including by looking at their mass, vibrational mode, or radioactive decay. Infrared spectroscopy measures the difference in an isotope's vibrational modes, whereas mass spectrometry measures the difference in the isotope's mass. Atoms with various gyromagnetic ratios can be found via nuclear magnetic resonance. Ionization chambers or gel autoradiographs can be used to detect radioactive decay. The study of phenol (C6H5OH) in water using deuterium in place of common hydrogen (protium) is an illustration of the application of isotopic labelling (deuterium labeling). Phenol easily performs hydrogen-exchange reactions with water, as shown by the substitution of deuterium for the hydrogen in the hydroxyl group of the compound when it is added to deuterated water (water that contains D2O in addition to the normal H2O). The fact that just the hydroxyl group is impacted shows that the exchange events do not involve the other 5 hydrogen atoms.