Tritiated planar carbon forms and their production are provided. Methods are provided for the stoichiometrically controlled labeling of planar carbon forms capitalizing on normal flaws of carboxylic acids ubiquitously present in commercial preparations of these planar carbon forms. Alternative methods include generation of a metallated intermediate whereby a metal is substituted for hydrogen on the carbon backbone of a planar carbon form. The metalized intermediate is then reacted with a tritium donor to covalently label the planar carbon form. The tritiated planar carbon forms produced are useful, for example, for determination of a biological property or environmental fate of planar carbon forms.