Analysis of Geological Materials for Rare Earth Elements on the PlasmaQuant MS Elite Application Note · PlasmaQuant MS Elite

Summary

In recent years, there has been a rising demand for rare earth elements (REEs) in the fields of user electronics, catalysis, optical displays, high-performance magnets, batteries, aerospace manufacturing and medical applications. Hence, there is the need for reliable trace analysis procedures in the assessment of potential mining sites, process control solutions (largely comprising of rare earth oxides, REO) and quality control of high-purity REEs. Furthermore, there is a large interest in academic research in earth sciences involving trace and ultra-trace level determination of REEs in geology, geochemistry and mineralogy.

Inductively Coupled Plasma – Mass Spectrometry (ICP-MS) is a popular analytical technique in the determination of REEs, from raw materials including soils, rocks and ores to impurities in highly refined rare-earth products.

The technique offers fast, multielement detection of REE at concentrations down to the parts-per-quadrillion (ppq) range. However, challenges often faced by scientists in the measurement of REE include the occurrence of polyatomic and isobaric interferences that are not resolved by quadrupole ICP-MS. Sample preparation can also impose some analytical constraints and must be considered in order to obtain accurate and precise analytical data.

REEs commonly suffer from polyatomic interferences that result from the formation of oxides and hydroxides of other REEs or from other matrix elements typically present in geological samples, like Barium (Table 1). This is particularly important for REEs such as Pr, Tb, Ho and Tm that have only one stable isotope available for measurement. Therefore, an effective interference management system is essential in removing polyatomic interferences and also negates the need for traditional mathematical correction of polyatomic interferences.

Within this study the PlasmaQuant® MS Elite was used to analyze five geological reference materials, including rock, stream sediment, shale, basalt and cement, regarding their REE content using the Integrated Collision Reaction Cell (iCRC) to remove polyatomic interferences.