IsotopenTracer

An isotopentracer is a chemical compound in which one or more atoms are replaced by their isotopes to serve as a label that can be tracked as the compound participates in chemical, biological, or environmental processes. Isotopentracers leverage either stable isotopes or radioactive isotopes, enabling observation without altering the system’s normal function or with controlled perturbation.

Stable-isotope tracers use non-radioactive isotopes such as 13C, 15N, 18O, or 2H. They are detected after sampling by techniques such as mass spectrometry or nuclear magnetic resonance, which reveal the incorporation and distribution of the label in metabolites, materials, or tissues. Radioactive tracers employ isotopes such as 3H, 14C, 11C, or 18F, and are detected via emitted radiation, imaging, or scintillation counting, often enabling real-time or highly sensitive measurements in vivo or in vitro.

Applications span metabolism and biochemistry, pharmacokinetics, environmental and earth sciences, and plant physiology. In medical imaging, 18F-labeled tracers such as 18F-FDG are widely used in positron emission tomography (PET) to visualize tissue metabolism. In research, 13C- or 15N-labeled substrates enable tracing of metabolic pathways and flux analysis through downstream MS or NMR data.

Design considerations include selecting the appropriate isotope and labeling position, achieving sufficient isotopic enrichment, and accounting for natural isotope abundance. Interpretation must consider potential isotopic dilution, physiological effects of labeling, and analytical uncertainties. Safety, regulatory factors, and cost also influence the choice between stable and radioactive tracers.