ANALYSIS OF LIQUID-PHASE TUNGSTEN HEXAFLUORIDE RESIDUE BY INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY WITH ULTRASONIC NEBULIZATION

A method was refined for the determination of trace elemental contamin ants in high-purity tungsten hexafluoride. The procedure is based on t he collection of a liquid-phase sample of WF6, generating a residue by evaporation of the sample and subsequent digestion in concentrated am monia solution. After sample digestion and workup, analysis was perfor med by inductively coupled plasma mass spectrometry (ICP-MS) with ultr asonic nebulization. The reliability of the analysis method and instru ment limits of detection were found to be superior to ICP-MS with a pn eumatic nebulizer and water-cooled spray chamber. The following limits of detection (in ng cm-3) were observed: Na, 0.2; Mg, 0.01; P, 3.2; K , 1.5; Cr, 0.02; Fe, 0.5; Ni, 0.03; Cu, 0.08; As, 0.07; Pb, 0.01; Th, 0.02; and U, 0.03.