How do we ascertain specific activities in no-carrier-added radionuclide preparations?

In nuclear and radiochemistry the concepts of specific activity, radioactive concentration, isotopic and non-isotopic carrier, carrier-free and no-carrier-added are of paramount relevance. In fact, traces of carrier are easily introduced in the radioactive preparations by their presence in the target material, by equipment and chemicals used in target processing, and may also be produced by side nuclear reactions induced in the target by nuclear activation, sometimes followed by a decay chain. Very sensitive analytical and radioanalytical techniques allow the determination of the real value of specific activity of no-carrier-added radionuclides and labeled compounds. Thus, in this paper we show with several examples that in most practical cases the term carrier-free (CF) is used improperly and has to be substituted by the more suitable term no-carrier-added (NCA). Carrier-free radionuclides and labeled compounds do exist in a few selected cases only.