Abstract Blue solutions containing 15 labelled bis (polyfluoralkyl) nitroxides and spin traps, polyfluoronitrosoalkanes, were conveniently made from the reactions of Na 15 NO 2 with polyfluoro-compounds,(RF CO 2) and RF SO 2 Br in F113. It has been found that the nitroxides effected fast H-abstraction from alkanes, alkylbenzenes, aldehydes and the radicals derived from the substrates were in turn effectively trapped by RF 15 NO to give ...