Analysis of Cerium Oxide by Mass Spectrometry and Optical Emission Spectrometry with Inductively Coupled Plasma

Procedures are developed for the multielement analysis of high-purity cerium oxide for the manufacture of phosphors and optical materials using inductively coupled plasma–mass spectrometry (ICP–MS) and inductively coupled plasma–optical emission spectrometry (ICP–OES). The “robust” settings of the mass spectrometer are given suitable to determine Fe, Ni, Cr, Co, Cu, V, Mn, and rare-earth metals in cerium oxide (nebulizer gas flow, liquid flow, plasma sampling depth, the extract lens voltage), lowering the matrix effect and, therefore, enabling the use of more concentrated solutions for analysis. The effect of the matrix element in the direct analysis of cerium oxide by ICP–OES is estimated. The combination of mass spectral and atomic emission methods has some advantages, expands the range of elements to be determined, and increases the reliability of the analysis. In particular, the use of ICP–OES makes it possible to determine low concentrations of terbium in cerium oxide (the limit of determination for terbium by ICP–OES is 1 × 10 –4 wt %) and decreases the limits of determination for Fe and Pr by a factor of 4–5 compared to ICP–MS. The limits of determination of the target components (Fe, Ni, Cr, Co, Cu, V, Mn, and rare-earth metals) in cerium oxide by ICP–MS and ICP–OES are in the range of n × 10 –6 – n × 10 –4 wt %.