Separation and Preconcentration of Impurities in Rare-Earth-Based Materials for Spectrometric Methods

The efficiency of using rare earth metals largely depends on their impurity composition, which affects the structure and properties of materials. Before the analytical control of materials based on rare earth elements (REEs) and the starting materials for their production, the task is to determine both macrocomponents with high accuracy and impurities with high sensitivity, correctness, and precision. To determine the impurities in REE-based materials in the range from 10^–5 to 5.0 wt %, a complex of methods of atomic emission and mass spectral analysis is frequently used. However, the analysis of REE-based materials, even using these modern highly sensitive methods, is a difficult task due to spectral and matrix interferences. Therefore, different separation/preconcentration procedures are needed to determine both rare earth and non-rare-earth impurities. This article reviews publications of preconcentration methods for spectral and mass spectral methods of analysis of materials based on REEs and some other analytical methods. It is shown that the most common approaches are liquid extraction and chromatography. Sorption, cloud-point extraction, and precipitation are also used. There is no universal approach. Each method discussed in this article has its advantages and limitations. The analytical completion of the method confirms the effectiveness of the selected separation/preconcentration method in each specific case.