Determination of hafnium and zirconium in geological materials by neutron activation analysis

In this work, neutron activation analysis was applied to analyze the geological standard materials: GSP-1 and W-1 from USGS, GB-1 and BB-1 from the University of Bahia, Brazil and a sample of uraniferous rock. Hf was determined by instrumental method and the obtained results was shown with relative standard deviations varying from 1.1 to 14%. In the case of Zr analyses, both instrumental and radiochemical neutron activation analyses were used. The interference of Eu-154 radioisotope that emits gamma-rays too close to those emitted by Zr-95 was eliminated by retention of Zr in an anionic exchange resin column. The contribution of uranium fission product was considered in the Zr determination by using an interference factor. Results of Zr were presented with relative standard deviations varying from 2.0 to 25.7%. More precise results were obtained by using radiochemical separation. The concentration obtained for Hf and Zr in reference materials agreed well with respective certified values or information values.