isotopelabelled

Isotopically labeled compounds are molecules in which one or more atoms have been replaced by isotopes of the same element. These isotopes are atoms of the same element with a different number of neutrons, resulting in a different atomic mass. The most common isotopes used for labeling are stable isotopes like deuterium (a hydrogen isotope with one proton and one neutron), carbon-13, and nitrogen-15. Radioactive isotopes, such as carbon-14 and tritium, are also frequently employed.

The key principle behind isotopelabeling is that the chemical properties of a molecule are largely determined by its electron configuration, which is unaffected by the number of neutrons. Therefore, an isotopically labeled compound will behave chemically almost identically to its unlabeled counterpart. However, the difference in atomic mass or radioactivity allows for the detection and quantification of the labeled compound using specialized analytical techniques.

Stable isotope labeling often utilizes mass spectrometry to distinguish between the labeled and unlabeled molecules based on their mass-to-charge ratio. Radioactive isotopes are detected through their emitted radiation, typically using scintillation counters or autoradiography. This ability to trace and measure the presence of the labeled molecule makes isotopelabeling a powerful tool in various scientific disciplines.

Applications of isotopelabeling are widespread. In medicine, it is used for diagnostic imaging (e.g., PET scans with carbon-11 or fluorine-18), pharmacokinetic studies to track drug metabolism and distribution, and in metabolic research. In chemistry, it aids in elucidating reaction mechanisms and studying molecular transformations. Biology extensively uses isotopelabeling to investigate metabolic pathways, protein synthesis, gene expression, and environmental fate studies.