TY - JOUR
T1 - Determination of titanium isotopes in rutiles with high spatial resolution by femtosecond laser ablation multi-collector inductively coupled plasma mass spectrometry
AU - Liu, Hong
AU - Zhang, Wen
AU - Deng, Zhengbin
AU - Hu, Zhaochu
AU - Schiller, Martin
AU - Bizzarro, Martin
AU - Liu, Yongsheng
AU - Luo, Tao
AU - Feng, Yantong
AU - Feng, Lanping
N1 - Publisher Copyright:
© 2023
PY - 2023
Y1 - 2023
N2 - Crystallization of Fe–Ti oxides can induce significant Titanium (Ti) isotope fractionation during magmatic differentiation. As such, rutile (TiO2), a common Ti-rich mineral present in igneous, metamorphic, and sedimentary rocks, can serve as a tracer of the geologic processes. A new method to determine the Ti mass-dependent isotope fractionation of rutiles with high precision and high spatial resolution was developed using femtosecond laser ablation multi-collector inductively coupled plasma mass spectrometry (fs-LA-MC-ICP-MS). A high sensitivity cone combination (Standard sampler cone + X skimmer cone) can increase the Ti signals, which permits ablation of rutiles with a low ablation frequency of 1 Hz and analysis with high spatial resolution. However, a signal smoothing device is necessary to overcome the signal fluctuation issue that commonly occurs in the modern low-dispersion ablation cell at a low ablation frequency. Our results show that changing laser parameters (spot size and laser fluence) or signal mismatch between samples and references would bias toward higher δ49Ti values (0.16‰ to 0.59‰) in dry plasma, which can be suppressed by using wet plasma conditions instead. After these optimizations, the spatial resolution of our method at horizontal- and vertical-axis can be promoted to 10 μm and ≈4 μm, respectively, meanwhile ensuring accurate δ49Ti results with a precision of ±0.10‰. The long-term measurements of a rutile USA75 by fs-LA-MC-ICP-MS show a good reproducibility of δ49Ti (±0.11‰). Measurements of 9 natural rutile crystals by both solution MC-ICP-MS and fs-LA-MC-ICP-MS provide consistent δ49Ti values, confirming the robustness of our fs-LA-MC-ICP-MS method. A significant variation of δ49Ti (up to ≈2.94‰) among the 12 rutiles was observed, indicating that Ti isotopes in rutiles can be a useful geochemical tracer. Four rutile crystals (e.g., USA75, Bra12, Sco2 and Bra6) are shown to be homogeneous in δ49Ti within an uncertainty of <0.13‰ and can therefore serve as reference materials for future in situ Ti isotope ratios measurement.
AB - Crystallization of Fe–Ti oxides can induce significant Titanium (Ti) isotope fractionation during magmatic differentiation. As such, rutile (TiO2), a common Ti-rich mineral present in igneous, metamorphic, and sedimentary rocks, can serve as a tracer of the geologic processes. A new method to determine the Ti mass-dependent isotope fractionation of rutiles with high precision and high spatial resolution was developed using femtosecond laser ablation multi-collector inductively coupled plasma mass spectrometry (fs-LA-MC-ICP-MS). A high sensitivity cone combination (Standard sampler cone + X skimmer cone) can increase the Ti signals, which permits ablation of rutiles with a low ablation frequency of 1 Hz and analysis with high spatial resolution. However, a signal smoothing device is necessary to overcome the signal fluctuation issue that commonly occurs in the modern low-dispersion ablation cell at a low ablation frequency. Our results show that changing laser parameters (spot size and laser fluence) or signal mismatch between samples and references would bias toward higher δ49Ti values (0.16‰ to 0.59‰) in dry plasma, which can be suppressed by using wet plasma conditions instead. After these optimizations, the spatial resolution of our method at horizontal- and vertical-axis can be promoted to 10 μm and ≈4 μm, respectively, meanwhile ensuring accurate δ49Ti results with a precision of ±0.10‰. The long-term measurements of a rutile USA75 by fs-LA-MC-ICP-MS show a good reproducibility of δ49Ti (±0.11‰). Measurements of 9 natural rutile crystals by both solution MC-ICP-MS and fs-LA-MC-ICP-MS provide consistent δ49Ti values, confirming the robustness of our fs-LA-MC-ICP-MS method. A significant variation of δ49Ti (up to ≈2.94‰) among the 12 rutiles was observed, indicating that Ti isotopes in rutiles can be a useful geochemical tracer. Four rutile crystals (e.g., USA75, Bra12, Sco2 and Bra6) are shown to be homogeneous in δ49Ti within an uncertainty of <0.13‰ and can therefore serve as reference materials for future in situ Ti isotope ratios measurement.
KW - fs-LA-MC-ICP-MS
KW - High spatial resolution
KW - Microanalysis
KW - Rutile
KW - Ti isotopes
U2 - 10.1016/j.sab.2023.106646
DO - 10.1016/j.sab.2023.106646
M3 - Journal article
AN - SCOPUS:85149434725
VL - 202
JO - Spectrochimica Acta Part B: Atomic Spectroscopy
JF - Spectrochimica Acta Part B: Atomic Spectroscopy
SN - 0584-8547
M1 - 106646
ER -