Term: specifically labelled
https://doi.org/10.1351/goldbook.S05793

Definition:
An isotopically labelled compound is designated as specifically labelled when a unique isotopically substituted compound is formally added to the analogous isotopically unmodified compound. In such a case, both position(s) and number of each labelling nuclide are defined.

Related Terms:
1) isotopically labelled (http://doi.org/10.1351/goldbook.I03336).
2) isotopically substituted (http://doi.org/10.1351/goldbook.I03338).
3) isotopically unmodified (http://doi.org/10.1351/goldbook.I03339).
4) nuclide (http://doi.org/10.1351/goldbook.N04257).
5) labelling (http://doi.org/10.1351/goldbook.L03425).

Source: Blue Book, p. 514 (https://www.acdlabs.com/iupac/nomenclature/)

Citation: 'specifically labelled' 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.S05793

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