Direct trace element analysis of tungsten powders, alloys and related materials by inductively coupled plasma atomic emission spectrometry (ICP-AES)

Abstract

A method for the direct analysis of pure tungsten metal and oxide powders and related materials by inductively coupled plasma atomic emission spectrometry (ICP-AES) is described with emphasis on line selection. Metal samples are decomposed using hydrofluoric and nitric acids, oxides are dissolved employing hydrogen peroxide and related complex materials using a sodium peroxide fusion or a mixed-acid technique. Solutions are injected into a HF-resistant sample introduction system and torch. It will be shown that the use of a tungsten ion line as an internal reference for simultaneous multi-element analysis of pure tungsten can compensate for fluctuations in background intensity, resulting in the improvement of the limits of detection. For the analysis of complex materials, the use of a high-resolution sequential monochromator facilitates line selection. Trace element analytical data compare favourably with recommended values when the concentration is 10–20 times the limit of detection in a tungsten solution. Limits of detection and analytical data are compared with those obtained by direct current plasma, flame and furnace atomic absorption spectrometries, and direct current carbon arc emission spectrography.