For the determination of Ag, Br, Co, Cr, Cs, Fe, Na, Rb, Sb, Se and Zn in biological materials by gamma-spectrometry of long-lived
radionuclides after long-time irradiation with thermal neutrons, irradiation vials of high purity silica were used so that
the samples could be analysed without the containers being removed. The accuracy and precision of the procedure were tested,
using the standard reference material “Bovine Liver” and identical serum samples. In the case of blood serum the method proved
to be suitable for the determination of Br, Cs, Fe, Na, Rb, Se and Zn. By analysing samples from several subjects information
about element levels in human serum was obtained.