Neutron activation analysis of nickel purified by floating zone-refining and anion exchange.

Nondestructive neutron activation analysis was performed on the nickel purified by floating zone-refining and anion exchange. It is found that floating zone-refining in vacuum is effective to remove Na, Sc, Cr, Zn, As, Ag, Sb and Hg through vaporization in addition to elimination of Se, Sb, Ta, Sm and Tb through segregation. Anion exchange method is also effective to separate Fe, Co, Zn, Mo, Hg, Th and U usually contained in the commercial nickel sources. It is concluded that combination of these two purification methods is required to obtain high purity nickel, since floating zone-refining is known ineffective to eliminate Fe and Co, main impurities in commercial nickel sources.

Study on trace impurity elements in highly purified iron and aluminum by neutron activation analysis.

Activation analysis was carried out on the purified iron and aluminum to study the behavior of trace impurities on purification process, and to estimate the purity of the purified samples. Thermal neutrons with high Cd ratio through D2O column or graphite column were used for the activation of samples to reduce the interference effects by fast neutrons, the reactions, (n, p) or (n, a), from matrix elements. On the zone refined aluminum, the segregation of impurity elements was cleary observed. In the case of iron, decrease of impurity content was confirmed on superposing the various purification processes.

Determination of thorium series nuclides in thorotrast patients.

Application of gamma-ray spectrometry with a Ge(Li) detector and then instrumental neutron activation analysis to tissue samples from a Thorotrast patient using the same standard reference sample makes it possible to determine both 232Th concentrations and activity ratios of the descendant nuclides to 232Th in living tissues. This analytical method is nondestructive, being simpler and more reliable than the methods previously used. In the present study, the activity ratio of 228Ra/232Th in living tissue was estimated at 0.37 to 0.44, being somewhat lower than the value reported by Kato. As for the activity ratio of 228Th/228Ra, our value agreed fairly well with Kato's value. A stomach sample from a Thorotrast patient was found to contain the same level of 232Th as liver and spleen samples; trace amount of 232Th was also found in kidney and brain samples.