The determination of selenium in biological material by thermal neutron activation analysis and atomic absorption spectrometry

Neutron activation analysis and atomic absorption spectrometry (graphite furnace) methods for the analysis of selenium in human tissue are described. The sensitivity (10–30 ng/sample), accuracy and precision are of the same order for both techniques and the choice can only be made on grounds of urgency or convenience. AAS should be chosen for the analysis of wet tissue or the urgent analysis of small numbers of dry tissue. NAA should be chosen for the analysis of large numbers of dry tissue samples where time is not important. The selenium concentration of human liver is shown to be in the region of 1 to 2 ppm (dry weight). Selenium may be lost from tissue during freeze drying if the samples are not maintained at −35°C.