Determination of selenium in biological materials by neutron activation analysis using sup(77m)Se

The method for the rapid, precise and routine determination of selenium in biological materials was investigated by means of instrumental neutron activation analysis using the short lived sup(77m)Se (Tsub(1/2) = 17.5 s). The each sample was irradiated for 10 s in a pneumatic system at Musashi Institute of Technology Research Reactor in a thermal neutron flux, 1 x 1012 n cm-2 s-1. After about 30 s from the end of the irradiation, gamma-rays were counted for 30 s using a 15% relative efficiency Ge(Li) detector, of resolution 2.0 keV at 1332 keV, which was coupled with a multichannel analyzer to accumulate 0 -- 1000 keV gamma-rays in the 0 -- 2000 channels. The reproducibility in the irradiation and the measurement was (4 -- 5)% as the coefficient of variation. Under the various conditions of cooling time, counting time and selenium contents, the spectra analysis program for the decay and dead time correction was examined and found to be reliable for our purpose. Selenium in NBS Bovine Liver was nondestructively determined by the present method, and selenium content was found to be (1.07 +- 0.11) μg/g (NBS certified value: (1.1 +- 0.1) μg/g). Selenium in mouse organs and fish was also determined precisely within about two min. It can be concluded that the present method allows us to carry out the determination of selenium in biological materials precisely as a rapid routine work. (auth.)