Small amounts of radionuclides of suitable half‐life can be used to observe the kinetics of mass transport and isotopic exchange in the equilibrium distribution of a (micro‐)component between coexistent phases.
Quantitative assay of radioactivity is sensitive, precise and accurate and usually performed instrumentally. Though handling of radionuclides is restricted to authorized laboratories only, the combination of its potential and simplicity makes the radiotracer method an indispensable part of modern analytical chemistry.