Multi-element characterization of high-purity titanium dioxide by neutron activation analysis

A radiochemical neutron activation analysis method for the determination of 34 elements in titanium dioxide has been developed. For the assay of indicator radionuclides with short and with long half-lives, the radiochemical separation was performed by anion exchange on a Dowex 1 × 8 column and by combination of cation and anion exchange on a Dowex 50W × 8 and a Dowex 1 × 8 column from HF- and HF/NH₄F-medium, respectively. With both separation modes, a selective removal of the matrix-produced radionuclides ⁴⁶Sc, ⁴⁷Sc and ⁴⁸Sc was achieved. A selective extraction of copper with dithizone from 15 mol/L HF enabled counting the intensive but unspecific 511-keV rays of ⁶⁴Cu for the determination of Cu. The limits of detection achieved were between 0.004 ng/g for Sm and 0.8 μg/g for Sn (via ¹²⁵Sb). The elements La, Mn and Th were determined by instrumental neutron activation analysis only. These techniques were applied to the analysis of two titanium dioxide samples of different purity grade. The results and limits of detection are compared with those of other methods.