TRACE-ELEMENT DETERMINATION IN HIGH-PURITY SCANDIUM BY NEUTRON-ACTIVATION ANALYSIS AND PREIRRADATION MATRIX SEPARATION

A pre-irradiation separation procedure has been developed for the determination of trace elements in high-purity scandium by neutron activation analysis. The sample is dissolved in high-purity concentrated hydrochloric acid and scandium is extracted with the same volume of a solution of 50 vol.% bis(2-ethyl hexyl)-orthophosphoric acid (HDEHP) in toluene. The scandium matrix is removed from the most important trace impurities and the residual amount of Sc is in the range of 0.001%. The separation is carried out in the vial to be used in irradiation to prevent sample contamination. Detection limits in the ppb range were achieved with a sample of 10 mg, a thermal neutron flux of 2 . 10(13)n . cm(-2). s(-1) and an irradiation time of 48 hours. Most of the elements sought in two samples of high-purity scandium were below the detection limits.