Production oriented method for the determination of rare earth and other trace elements in rocks by ICP-MS.

Abstract

The rare earth elements along with Y, Sc, Co, Hf, Nb, Rb, Ta, Th, Ti, U, V and Zr have been determined in ten standard reference materials and ten granitoid samples by inductively coupled plasma mass spectrometry (ICP-MS). Two digestion methods have been used: (a) dissolution with hydrofluoric-perchloric acid followed by fusion of the residue with lithium metaborate, (b) dissolution with hydrofluoric acid-perchloric acid followed by fusion with lithium metaboratesodium perborate and addition of hydrogen peroxide. An evaluation of the two decomposition methods and a comparison of the ICP-MS and X-ray fluorescence results have been carried out. In comparing the two digestion methods, method (b) gave more accurate results for Nb and Ta, and it has been applied to a rock geochemistry project covering whole Finland (about 7000 samples). The statistical stability of the method has been monitored by frequent analyses of reference material SDC-1 (Mica Schist, USGS).