Combination and optimization of the cyclic NAA modes at the Dalat research reactor for determination of selenium in biological materials using 77mSe

The combination and optimization of the cyclic modes in neutron activation analysis (NAA) at the Dalat research reactor were performed to determine short-lived nuclides. This work focused on determination of selenium in biological materials using 77m Se ( T 1/2 = 17.4 s) as a case in point. The detection limit was significantly improved by a factor of 3–4 times in comparison with the conventional NAA. The precision was typically within the range of 4–6 % at the third or fourth cycle. It is a reliable technique for determination of selenium in biological materials at sub-ppm concentration levels.