Determination of Rare Earth Elements, Yttrium, Thorium, and Other Trace Elements in Monazite Samples by Inductively Coupled Plasma Mass Spectrometry

Analysis of monazite, an important mineral of rare earth elements (REEs), and thorium constitutes one of the toughest tasks in analytical chemistry as it is a highly resistant mineral and extremely difficult to completely decompose. In the present work, inductively coupled plasma mass spectrometry (ICP-MS) was applied to the determination of all individual REEs as well as other constituents like thorium, uranium, and zirconium in monazite samples originating from different places on the coast of India. Two different sample decomposition methods were used: one employing sulphuric acid decomposition and another using a fusion with a mixture of KHF2 and NaF in a 3:1 ratio. A mathematical correction scheme based on oxide yield and abundance data was applied to correct for the mass spectral interferences of LREE oxide ions on HREE ions.