Abstract:In the analysis of high purity rare earth element, C272 microcolumn separation or TODGA separation matrix is usually used to enrich the element to be measured, but this method is inefficiency and difficult to operate, and it is easy to introduce external impurities and incomplete elution, leading to deviations in results. In this paper, a test method for rare earth elements in high purity cerium trioxide (Ce2O3) by inductively coupled plasma mass spectrometry (ICP-MS/MS) was established. The collision mode was used to determine Y、La、Nd、Sm、Eu、Dy、Ho、Er、Tm、Yb、Lu and the mass shift mode was used to determine Pr、Gd and Tb in the Ce2O3 The test used 0.1% matrix injection in the MS/MS mode, and nitrous oxide (N2O) was used as the reaction gas through mass shift reaction of O and N atoms. It can effectively overcome the mass spectrum interference caused by high matrix and achieve accurate determination of 14 impurity rare earth elements in high purity Ce2O3 Under optimized experimental conditions, the detection limits of fourteen elements were in the range of 0.001~0.020mg/kg, the recoveries were in the range of 81.2%-105.3%. The developed method can determine impurity elements in high purity rare earth oxides quickly and accurately, and provide a way for the analysis of impurities in high purity rare earth oxides.