ICP-MS direct determination of trace amounts of rare earth impurities in various rare earth oxides with only one standard series

An inductively coupled plasma mass spectrometry (ICP-MS) method with just one standard series for direct determination of trace rare earth impurities in various rare earth oxides was developed. The spectral interference in ICP-MS analysis of high-purity neodymium (Nd2O3) was thoroughly estimated. For the investigation of matrix effect, high-purity Y2O3 was used as model sample and the experimental results showed that the maximal matrix tolerant amount obtained by stepwise dilution method is comparable to that obtained by conventional method with the use of higher purity Y2O3 as matrix. Under the selected conditions, no obvious matrix effect can be found with the matrix (Y) concentration of less than 500 μg mL−1. For real sample analysis, 100 μg mL−1 of matrix was chosen as the sample concentration. The proposed method was applied to the analysis of trace rare earth impurities in different high-purity rare earth oxides (Y2O3, Pr6O11, Nd2O3, Dy2O3, Er2O3), and the analytical results obtained were in good agreement with the recommended values. The detection limits of the method for rare earth elements were 1-21 ng L−1 with the R.S.D varying between 2.9 and 7.8%, and the percentage recovery ranged from 93 to 115% for the spiked samples. This method was characterized with simplicity, rapidity, sensitivity, small sample amount required, and no internal standard/matrix matching requirements.