Analysis of metals in the non-volatile residue of liquid phase WF6

An improved method has been developed to analyze the metallic contaminants in the non-volatile residue of liquid-phase tungsten hexafluoride (WF6). Th is method uses a mixture of aqueous ammonia, aqueous hydrofluoric acid and aqueous nitric acid to dissolve the non-volatile residue, left behind when liquid-phase WF6 is evaporated. The use of this aggressive mixture is much superior to the use of deionized water or aqueous ammonia, as has been the practice in the past. Using this aggressive matrix on the residue from a 22 0 g aliquot of WF6, and analyzing the solution using a quadrupole-based ICP -MS instrument equipped with an inert sample introduction system, the follo wing limits of detection are obtained: Na 0.5; K 1.3; Fe 0.8; Cr 0.7; Th 0. 01; and U 0.01 ng g(-1) WF6.