nominally labelled tracer

https://doi.org/10.1351/goldbook.N04178
A @T06422@ in which the @L03424@ is present mainly in a specified position.
Source:
PAC, 1994, 66, 2513. (Nomenclature for radioanalytical chemistry (IUPAC Recommendations 1994)) on page 2526 [Terms] [Paper]