The selection of a tracer depends on the specific objectives of the study. Isotopic tracers like 13C, 15N, or 18O are often used because they do not alter the chemical properties of the molecules but can be detected using mass spectrometry or NMR spectroscopy. In some cases, fluorescent or radiolabeled compounds may be used. The key is to choose a tracer that is chemically similar to the reactants or products but distinguishable by analytical techniques.
