HIGH-PRECISION AND ACCURATE DETERMINATION OF LU AND HF CONCENTRATIONS AND HF ISOTOPIC COMPOSITIONS AT THE SUB-NANOGRAM LEVEL IN GEOLOGICAL SAMPLES USING MC-ICP-MS
The motivation of this work is to establish a simple, rapid and practical analytical protocol for Lu and Hf concentrations and Hf isotopic compositions of sub-nanogram level Lu and Hf in geological samples using MC-ICP-MS, without comprising the precision and accuracy. Samples were spiked with 176Lu-180Hf enriched tracer, followed by the complete digestion using the conventional HF, HNO3 and HClO4 acid protocol and then complete dissolution fluoride formed during the HF decomposition step using H3BO3. Mass spectrometric measurement was carried out on a Neptune Plus MC-ICP-MS with Aridus II desolvator. In order to demonstrate the robustness of present protocol, six rock reference materials (RMs) of UB-N, JP-1, NIM-D, MUH-1, HARZ01 and DTS-2b, encompassing various rock types with very low amounts of Lu and Hf (from nanogram to sub ng g-1 level), were multiply analyzed with full column chemistry. The analytical results of the geological RMs are in good agreement with the published values. Combined with highly efficient and low-blank chemistry, this protocol greatly holds potential analysis in high-precision and accurate determination of Lu and Hf concentrations and Hf isotopic compositions at the sub-nanogram level in geological samples using MC-ICP-MS.