Radiochemical separation of7 5Se with o-phenylenediamine for instrumental neutron activation analysis of selenium in biological materials

A new method of radiochemical separation for determination of selenium in biological materials has been developed. The method is based on the reaction of tetravalent selenium with the amino groups of aromatic ortho-diamines resulting in selenodiazoles, which can be easily extracted with organic solvents. The biological samples were irradiated in a reactor, mineralized with nitric and perchloric acids and MgCl₂. Selenium was transformed to teravalent form with hydrochloric acid and the resulting bezoselenodiazole formed in the reaction with o-phenylenediamine was extracted with toluene. The radioactivity of selenium^{7 5}Se was measured with a well-type NaI(Tl) scientillation detector. The accuracy of the method was verified by determining selenium levels in SRM NBS. The detection limit of the method was found to be 0.5 ng Se. The comparison of selenium levels in human blood determined by HG-AAS. non-destructive NAA and the described method is presented.