Determination of impurities in niobium metal by a radiochemical neutron activation analysis

A radiochemical separation method using an anion exchange resin has been applied to 3N grade Nb for determining nine impurity elements. Five elements (Cr, Fe, Co, Zn and Se) were separated in 2M HF, three elements (Mo, W and Hf) in 32M HF, Nb in 0.5M HF/3M HCl, and Ta in 1M NH₄F/4M NH₄CCl. The contents of the elements were calculated by a single comparator method using two monitors of Au and Co. The main impurity was revealed to be Ta with a content of over 160 ppm.