Direct analysis of tungsten in crude niobium pentoxide using microwave digestion and ICP-OES

Niobium Pentoxide (Nb 2 O 5 ) is prepared from feed raffinate solution of tantalum solvent extraction. The major impurities, which are associated with niobium pentoxide, are tantalum, tungsten, titanium and iron. While analyzing tungsten by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) niobium interference free lines has to be selected first and this line should also be free from the interference of tantalum, titanium and iron. The interference free line thus selected (224.875nm) has been analyzed for its accuracy and preciseness by analyzing I mg/L tungsten doped into 1000 mg/L Nb, 100 mg/L to 500 mg/L Ta, Ti and Fe the results are presented along with a pictorial depiction of spectral interferences by Nb, Ta, Ti and Fe for interference free line selection of tungsten. Nb 2 O 5 being ceramic in nature dissolving in open digestion is very difficult and time consuming, here a simple and rapid method of dissolution by microwave digestion (MDS) is adopted.