Analysis of ZrO2 powders by microwave assisted digestion at high pressure and ICP atomic spectrometry

Microwave assisted digestion at high pressure was investigated for the diss olution of different ZrO2-based ceramic powders and their subsequent analys is performed by inductively coupled plasma optical emission spectrometry (I CP-OES) and mass spectrometry (ICP-MS). For a fine grain size ZrO2 powder ( median particle size <1.9 mu m) the results were found to well agree with t hose obtained in the case of conventional digestion at high pressure, decom position by fusion with NH4HSO4 and slurry nebulization ICP-OES. In the cas e of microwave assisted digestion at high pressure, up to 600 mg of ZrO2 co uld be dissolved within only 60 min, whereas by conventional digestion at h igh pressure up to 1000 mg ZrO2 powder could be dissolved; however, this re quired a time of 10 h. By fusion with NH4HSO4 it was not possible to dissol ve all of the ceramic powders investigated completely. For all investigated elements excepted for B and Si, recoveries of 100% were obtained within th e level of experimental error 3-13%. Detection limits, in the case of ZrO2 powders with high concentrations of Hf, Na and Y, were found to range from 0.03 mu g g(-1) for Mg, when applying conventional digestion at high pressu re, over 0.4 mu g g(-1) for Fe, in the case of microwave assisted digestion at high pressure, to 92 mu g g(-1) for Na in the case of slurry nebulizati on ICP-OES and 114 mu g g(-1) in the case of Y subsequent to decomposition by fusion. The results of analysis subsequent to the different dissolution methods and those obtained with slurry nebulization ICP-OES agreed well for the elements Cr, Fe, Hf, Mg, Na, Ti and Y. With quadrupole based inductive ly coupled plasma mass spectrometry Na could be determined at the 600 mu g g(-1) level and the results agreed well with those obtained by ICP-OES, whe reas for Al, Cr, Cu, Fe, Mg, Mn and Ni spectral interferences were found to hamper analyses. For Li, as well as for Ce, La, Pr and Th, it could be sho wn that the impurity levels in the samples analyzed were below 2 and 1 mu g g(-1), respectively.