Using instrumental neutron activation analysis, the variations in the serum levels of Br, Cs, Na, Rb, Se, and Zn were investigated
in 18 persons in the normal state. By determining the element levels in relation to changes is the serum water content, information
about the binding to the serum protein was obtained. The influence of physiological factors on the serum element levels was
investigated. Changes in the concentrations due to variations in the protein/water ratio and in the zinc level as a result
of different posture were observed. When standardized sampling procedures were used, the variations in the serum element concentrations
during one hour and from day were found to be less than 10%.
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.