In this paper, an in situ matrix separation method has been developed for the determination of trace rare earth impurities in high purity tantalum pentaoxide (Ta 2 O 5 ) by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS). A polytetrafluoroethylene (PTFE) slurry was used as a chemical modifier to convert both the matrix (Ta) and the rare earth elements (REEs) into their fluorides, with different volatilities, at high temperature in a graphite furnace. The more volatile TaF 5 was removed in situ by selective vaporization prior to the determination of the ana...
