generally labelled tracer

https://doi.org/10.1351/goldbook.G02613
A tracer in which the position of the label is not defined.
Source:
PAC, 1994, 66, 2513. 'Nomenclature for radioanalytical chemistry (IUPAC Recommendations 1994)' on page 2526 (https://doi.org/10.1351/pac199466122513)