Determination of ultra-low level rare earth elements in ultramafic rocks by ICP-MS

抄録

High precision REE data are seldom reported for mantle derived ultramafic rocks because of their ultra low concentrations and enigmatic spectral interference in ICP-MS determination. Large correction factors were usually needed to correct interferences and signal drift, consequently impaired the data quality and resulted in ambiguous geological interpretation. In this study, a simple method was established for the determination of ng g-1 level rare earth elements of ultramafic rock based on acid dissolution and conventional quadrupole ICP-MS with systematic interference corrections on each sample. The method was demonstrated with repeated analyses of geochemical reference materials (GRMs), including JP-1, DTS-1, DTS-2 and PCC1. Quantitation limits and procedural blanks were about 0.01-0.08 ppb and 0.2-5 pico-gram, respectively. Reproducibility obtained from separate dissolutions and measurements of GRM was 3-6%. Smooth chondrite-normalized REE patterns were obtained for the tested GRMs. Measured REE data of the GRMs were within the range of recently published ICP-MS data, and were quite consistent with high precision data obtained by sector field ICP-MS and ID-TIMS.