Derivative Neutron Activation Analysis (DNAA):
This method also called as Molecular Activation Analysis is used to enhance the sensitivity of NAA for more elusive elements, which are otherwise difficult to be determined by NAA. It has the advantage of being useful for studying chemical speciation. In this technique, an element or chemical entity to be determined (U) is complexed with, or exchanged for another element, which has higher sensitivity for NAA. Also the product radionuclide should have an interference free photopeak in low background region. It is desirable that the compound formed should be stoichiometric and it should be easily separable quantitatively. A DNAA procedure has been developed for the determination of phosphorus. It is complexed as molybdovanadophosphoric acid which is then extracted in MIBK and the activity of 52V (t1/2 = 3.4 min) is measured. Thus phosphorus which is otherwise difficult to be determined by NAA, can be determined indirectly.