Any molecular entity in which the isotopic ratio of nuclides for at least one element deviates measurably from that occurring in nature. The term includes both isotopically substituted compounds (in which essentially all the molecules of the compound have only the indicated nuclide(s) at each designated position) and isotopically labeled compounds (a formal mixture of an isotopically unmodified compound with one or more analogous isotopically substituted compound(s).
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This entity has been manually annotated by the ChEBI Team.
The isotope of an isotopically substituted compound is enclosed by parentheses in its name but not in its structural formula: (14C)methane, 14CH4 ; (1-2H1)ethanol, CH3-CH2H-OH ; etc.
2018-01-04
For specifically labeled compounds (when a unique isotopically substituted compound is formally added to the analogous isotopically unmodified compound), the structural formula is written with the appropriate nuclide symbol(s) and multiplying subscript, if any, enclosed in square brackets. Thus a formal mixture of 14CH4 and CH4 gives the specifically labeled compound [14C]H4