{"term":{"id":"08733","title":"isotopic label","longtitle":"IUPAC Gold Book - isotopic label","doi":"10.1351\/goldbook.08733","code":"08733","status":"current","mentioned":"<em>mentioned<\/em>: conjugation labelling, exchange labelling, recoil labelling","definitions":[{"id":1,"text":"Radioactive or stable isotope of a specified element distinguishable by the observer but not by the system used to identify an isotopic tracer.","notes":{"1":"'Isotopic labelling' is the incorporation of an isotopic label in a substance. It may be qualified by the manner of introduction of the label, e.g. exchange labelling, conjugation labelling, recoil labelling.","2":"In general usage, 'label' and 'tracer' are used synonymously."},"exams":{"1":"Deuterium ('isotopic label') that is substituted for protium in the illegal drug methylamphetamine, for use in analysis by mass spectrometry. Methylamphetamine incorporating deuterium is the 'isotopic tracer'."},"sources":["PAC, 2021, 93, 69. 'Vocabulary of radioanalytical methods (IUPAC Recommendations 2020)' on page 85 (https:\/\/doi.org\/10.1515\/pac-2019-0302)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/08733\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/08733\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/08733\/plain"},"citation":"Citation: 'isotopic label' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351\/goldbook.08733","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.","collection":"If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .","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.","accessed":"2026-05-18T03:41:22+00:00"}}