Comparison of neutron activation analysis, X-ray fluorescence spectrometry and inductively-coupled plasma mass spectrometry for the determination of rare earth element concentrations in Jordanian monazite ore

The analysis of rare earth element (REE) concentrations in geological ores and their downstream processed samples is critical to their successful isolation and deployment across a broad range of applications. There are a number of factors that must be considered in determining the most suitable analytical technique: in addition to accuracy of analysis, the range of elements that can be analysed and the sample preparation required are also important considerations. This study compares instrumental neutron activation analysis (INAA), X-ray fluorescence (XRF), and inductively coupled plasma mass spectrometry (ICP-MS) for the determination of rare earth element (REE) concentrations in Jordanian monazite. While INAA requires the least sample preparation, ICP-MS was able to analyse the broadest range of elements. All three techniques reported good recoveries across the REE series for two certified reference materials, with ICP-MS showing highest accuracy (recovery rates of 100-110% and 89-117%) and (average value deflection for REE-1 was 3.75% for ICP-MS, 5.06% for INAA, and 11.7% for XRF). Finally, comparison of the three techniques across processed monazite samples of varying concentration showed that ICP-MS was slightly superior to the other techniques, with no significant differences across sample concentrations or elements.