Analytical applications of furnace atomisation non-thermal excitation spectrometry (FANES) and molecular non-thermal excitation spectrometry (MONES). Part 3. Determination of rare earth elements by electrothermal atomisation atomic emission spectrometry (ETA-AAS), FANES and furnace Ionisation non-thermal excitation spectrometry (FINES)

Abstract

The application of two methods of trace analysis of microsamples, electrothermal atomisation atomic absorption spectrometry (ETA-AAS) and furnace atomisation non-thermal excitation spectrometry (FANES) to rare earth elements (REE) was studied. The evaporation and atomisation could be improved in both methods by the introduction of a tungsten platform into the graphite tubes to prevent the formation of REE carbides. Depending on the boiling-points of the REE, the absolute detection limits for both methods are in the picogram range. The thermal conditions for evaporation and atomisation were optimised. It was found that in ETA-AAS only the use of maximum heating conditions is successful. In FANES determinations on pure solutions the heating conditions can be reduced with the use of a vacuum, but in the presence of inorganic matrices it is again advantageous to use maximum heating. A new variation of FANES, furnace ionisation non-thermal excitation spectrometry (FINES), was developed for easily ionisable elements and was applied successfully to the determination of Eu, Sc and Sm. The limits of determination of REE in other REE are 1–100 p.p.m., depending on the conditions used, which were mainly influenced by the volatility of the elements.