Trace characterization of tantalum by NAA involving pre- and post-irradiation separations

Three different methods for pre-irradiation separation of the tantalum matrix combined with preconcentration of trace elements for NAA were developed. They involve selective extraction of tantalum with diantipyrylmethane, and anion- and cation-exchange from hydrofluoric acid medium. The role of the blank as the limiting factor for limits of detection and accuracy was one of the main aspects of this investigation. A conventional radiochemical NAA based on post-irradiation separation of the matrix radionuclides was also applied. The trace elements considered were Ag, Ba, Ce, Co, Cr, Cu, Eu, Hf, K, La, Mn, Mo, Na, Rb, Re, Sc, W, Y, Zn, Zr. The methods were used for the analysis of tantalum materials of different purity grades. The advantages and disadvantages of each technique are discussed and the achievable limits of detection are given.