Describes a compound that has a macroscopic composition such that the isotopic ratio
of
nuclides for at least one element deviates measurably from that occurring in nature. It is
either an
isotopically substituted compound or an
isotopically labelled compound.
Source:
PAC, 1981, 53, 1887
(Nomenclature of inorganic chemistry: II.1 - Isotopically modified compounds)
on page 1889