Trace Elemental Analysis Of High-purity Niobium, Bismuth And Tungsten By Glow Discharge Mass Spectrometry

The niobium, bismuth, tungsten are three important metal materials, which are widely used in electronics, military, nuclear industry and other industries. The rapid development of modern technology needs more high-purity metals, the purity requirements are increasingly strict, too. The purity of the metal plays a key role in the application of metal materials, and even trace impurity will influence the performance of metal materials. So the analytical methods of high-purity niobium, tungsten and bismuth should be put forward to higher requirements.Glow Discharge Mass Spectrometry (GD-MS) can analyse the solid sample directly, which has low detection limit, many analytical elements, wide testing scope, fast analysis speed and many other advantages. It has been recognized as the one of the best methods for testing trace element in high-purity metals.GD-MS method was applied in the experiment to determinate trace elements in high-purity niobium, bismuth and tungsten. The working conditions were optimized, For the high-purity niobium, the selected instrument working conditions were:Discharging current:35mA, Flow of discharging gas:0.45L/min; For the high-purity bismuth, the selected instrument working conditions were:Discharging current:10mA, Flow of discharging gas:0.45L/min; For the high-purity tungsten, the selected instrument working conditions were:Discharging current:45mA, Flow of discharging gas:0.44L/min. The detection limit of GD-MS method could reach at ng/g level, the determination of value could be tested from0.005μg/g to127.3μg/g, the Relative Standard Deviation (RSD) could be guaranteed within50%. It should be satisfied the requirements of testing high-purity niobium, bismuth and tungsten samples.In this experiment, after calculating the results of impurities tested by GD-MS, the purity of niobium, bismuth and tungsten samples were computed. The advantages of GD-MS between other trace impurity analysis methods were also discussed in this paper.Because of the lack of Certified Reference Material (CRM) for the GD-MS, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was also used to verify the accuracy of GD-MS results. The limits of detection in ICP-MS tests were from0.07to2.7ng/mL, determinations were in the range of0.3μg/g to126.1μg/g, the precisions were from3%to10%, and the recoveries percentage were from80%to108%. The main determination valves of high-purity niobium, tungsten and bismuth by ICP-MS were basically the same as GD-MS method.The experiment indicated that GD-MS methods are reliable to meet the requirements of the testing for high-purity niobium, tungsten and bismuth.