ISOTOPIC AND NUCLEAR ANALYTICAL TECHNIQUES IN BIOLOGICAL-SYSTEMS - A CRITICAL-STUDY .10. ELEMENTAL ISOTOPE-DILUTION ANALYSIS WITH RADIOACTIVE AND STABLE ISOTOPES

Isotope dilution is a method of-chemical analysis based on the mixing (or dilution) of a radioisotope or a separated stable isotope with its natural isotope(s) in the sample. The activity ratio or isotopic rati o of the mixture defines the concentration of the analyte, which is a tremendous advantage for measurement since quantitative separation of the analyte is not required. The technique has a multitude of variatio ns and has been combined with many classical and instrumental procedur es used in analytical chemistry. The technique is noted for its accura cy. This review focuses on the application of the technique in the det ermination of elemental concentrations in biological systems.