Instrumental Neutron Activation Analysis

Neutron activation analysis (NAA) is a sensitive analytical technique for performing qualitative and quantitative multi-element analysis of major, minor, and trace elements in samples of approximately 60 elements (30-40 elements simultaneously). For many elements and applications, NAA offers sensitivities that are superior to those attainable by other analytical techniques; a detection limit of 1-2 ppb is feasible. The reason for the high sensitivity of NAA is that most sample matrices appear to be transparent; H, C, O, N, P, and Si hardly form any radioactive isotopes. Because of this, it is not necessary to do any sample preparation other than size reduction and (in some cases) drying, making the technique non-destructive. Another advantage is that the technique requires only small amounts of sample material - 100 to 200 milligrams will do.

The method is based on the conversion of stable nuclides into radioactive nuclides (radionuclides) by irradiation with thermal neutrons (neutrons of low energy). These radionuclides stabilize by decline to stable nuclei by transmission of radioactive gamma-radiation. The energy of the gamma-radiation provides information on the radionuclide. The number of pulses (intensity) at certain energy is proportional to the concentration of the element in the sample. Measurement will be carried out at the 'Hoger Onderwijs Reactor' under Sterlab accreditation.