Term: direct (radiochemical) isotope dilution analysis https://doi.org/10.1351/goldbook.D01772 Definition: isotope dilution analysis used for the determination of a non-radioactive element with the aid of one of its radionuclides. Related Terms: 1) isotope dilution analysis (http://doi.org/10.1351/goldbook.I03323). 2) radionuclides (http://doi.org/10.1351/goldbook.R05116). 3) radioactive (http://doi.org/10.1351/goldbook.R05077). Source: PAC, 1994, 66, 2513. 'Nomenclature for radioanalytical chemistry (IUPAC Recommendations 1994)' on page 2521 (https://doi.org/10.1351/pac199466122513) Citation: 'direct (radiochemical) isotope dilution analysis' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.D01772 License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms. Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.