Utilisation of a WETA 82 tungsten atomiser for the determination of rare earth elements

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Abstract
Atomisation of rare earth elements (REE) in a tungsten atomiser proceeds mainly through thermal dissociation and reduction of REE oxides. Owing to the high heating rates of the tungsten cuvette, the atomisation process proceeds very quickly, it is therefore necessary to know its time dependence. The time dependencies of the absorbance signal were determined with a computer connected on-line to the spectrometer and atomiser. The following parameters were investigated: optimum rate of increase of the atomisation temperature, time and values of both decomposition and atomisation temperatures, optimum hydrogen and argon flow-rates, width of the spectral interval and mutual interferences of the REE and REE-tungsten interferences. Under the optimised conditions, the characteristic mass values were determined and found to be comparable with those obtained in a graphite atomiser coated with tantalum or tungsten foil.