Solution Nebulizer And Femtosecond Laser Ablation-multicollector Inductively Coupled Plasma Mass Spectrometry And The Application In The Geological Science

In this paper, we study the solution nebulizer and femtosecond laser ablation-multicollector inductively coupled plasma mass spectrometry (SN/fLA-MC-ICP-MS) and the application in geological science. Mainly in the following aspects:The experimental synthetic zircon Lu-Hf isotope reference material, to improve mass bias and isotope fractionation and interference correction parameters and procedures, so as to improve the accuracy and precision for zircon Lu-Hf isotope in-situ analysis; established Fe isotope separation and purification of the sample program by experiment, solution nebulizer (SN) and membrane desolvation solution nebulizer (DSN)-multicollector inductively coupled plasma mass spectrometry (SN/DSN-MC-ICP-MS) for Fe isotope analysis method have been explored by instrumental parameters and analytical method;266nm femtosecond laser ablation system coupled with multicollector ICP-MS (fLA-MC-ICP-MS) to explore laser ablation conditions and instrumental parameters for in situ microanalysis of Fe isotopes in geological samples, to establish fLA-MC-ICP-MS Fe isotope in situ analysis method;266nm femtosecond laser ablation-multicollector ICP-MS (fLA-MC-ICP-MS) was also used for study instrumental parameters and analysis conditions for Pb isotope in situ analysis, and established Pb isotopic fLA-MC-ICP-MS analysis method, and to carry out a part of NIST, USGS, MPI-Ding CGSG series of reference materials (or reference glasses) Pb isotopic composition and its homogeneity research work. On the basis of the methods research266nm femtosecond laser ablation-multicollector inductively coupled plasma mass spectrometry (fLA-MC-ICP-MS) was used for in situ micro analysis Pb isotope in Songshugou Qinling Group amphibolite rock; Fe isotope in olivine and pyroxene from Songshugou peridotite was also determined by in situ microanalysis and research.I. Nitrogen gas, for example, a thorough research works to explore the effection and mechanism of auxiliary gas in MC-ICP-MS isotope analysis.During MC-ICP-MS isotope analysis, Sr-Nd-Hf-Pb isotopic analysis for example, the addition of nitrogen gas can effectively improve the ion signal intensity (increased sensitivity), while reducing the effect of isotope mass discrimination (mass bias). Sensitization or inhibition of the ion signals intensity of the elements (or isotopes) dependent on the instrument’s operating conditions and the concentration of nitrogen gas (or gas flow rate). During Sr-Nd-Hf-Pb isotopic analysis small volume of nitrogen was added, Sr isotope mass number is the smallest, but the most sensitizing effect, the signal intensity can be increased to60%with the mass fractionation coefficient decreased by6%; Pb isotopic mass sensitizing effect weak signal intensity is only increased by less than10%and the mass fractionation coefficient decreased by9%; Nd isotope mass is medium, the signal sensitivity increased28%after the addition of nitrogen gas, while mass fractionation coefficient decreased by6%. Isotope ions after nitrogen gas on the mass number and the ionization energy of the signal enhancement effect with isotope (ion). The smaller the mass number and the greater the ionization energy, the stronger it’s sensitizing effect, contrary sensitizing effect is weaker.2. Experimental synthetic zircon Lu-Hf isotope reference material, to improve isotope fractionation and interference correction parameters and procedures, thereby improving the accuracy and precision for zircon Lu-Hf isotope in situ analysis.In this paper, a synthetic zircon and experimental methods and conditions of the add trace elements, and accurate determination of element content and Lu-Hf isotope composition in synthetic zircon. The use of zirconium oxide and lithium silicate as flux raw materials, molybdenum oxide, and lithium molybdate, and add elements of Hf, Lu, Yb, U, Th, Pb, etc., after mixing into a covered platinum crucible, muffle furnace950℃for72hours for the zircon crystal growth. Synthetic zircon crystals have a perfect tetragonal crystal form of the double cone, the laser Raman spectroscopy exactly the same as that of the zircon typomorphic mineral crystal. Trace elements concentrations and zircon Lu-Hf isotope ratios were determined by the LA-ICP-MS and LA-MC-ICP-MS analysis method respectively, the test results shown that the content of Lu, Hf and Yb elements between different particles and the same particle have smaller internal changes, relatively homogeneous; U, Th, Pb, and other elements of content between different particles within the same particles have a greater change; there are no difference for Lu-Hf isotopic composition between different and the same particles or in the interior of one particle,176Hf/177Hf ratios in the same batch of synthetic zircon are in good agreement with each other in2s uncertainties. The experimental synthesis of zircon is expected as the the new zircon Lu-Hf isotope reference materials for accurate determination of Lu-Hf isotope composition in natural zircons.3. Using266nm femtosecond laser ablation-multicollector inductively coupled plasma mass spectrometry (fLA-MC-ICP-MS) analysis techniques for Pb isotopic in situ microanalysis, instrument parameters and experimental conditions have been studied for the establishment of the Pb isotopic fLA-MC-ICP-MS in situ microanalysis, and carry out a part of NIST, USGS, MPI-Ding and CGSG series of reference materials (or reference glasses) Pb isotopic composition and homogeneity tests, based on Songshugou Qinling Group plagioclase amphibolite example to explore the Pb isotopic in situ microanalysis applied research work in geological science.First study Pb isotopic reference materials with copper matrix in copper-mine (e.g. chalcopyrite, chalcocite, and bornite) or metallic-copper. Laboratory preliminary study found that, CuPbll (GBW(E)02003), CuPb12(GBW02137), CuPbl3(GBW02138), CuPb14(GBW02139) and CuPbl5(GBW02140) national standard reference material Pb isotopic composition is relatively homogeneous, further examination of the Pb isotopic composition of this five samples by fLA-MC-ICP-MS analysis. The analysis results show that Pb isotopic composition in CuPbl2(GBW02137) is very homogeneous, all the external precision RSDs of Pb isotope ratios were less than90ppm, and it can be external reference material for Pb isotopic in situ micro-analysis in copper-mine samples with matrix of Copper.This study also explores the Pb/Tl molar ratio, laser energy, ablation frequency, carrier gas and laser ablation systems (nanosecond excimer laser and femtosecond laser), and mass discrimination correction strategy for Pb isotope analysis. The results shown that the Pb/Tl molar ratio of1.8to5.3can be obtained high-precision Pb isotope data, is the best ratio; laser energy and denudation frequency principal effects of Pb, Tl ion signal intensities, no greater impact for mass fractionation coefficients of Pb and Tl; carrier gas (Helium and Argon gas) has a greater impact on signal intensityies of Pb and Tl ions and mass fractionation factors, Helium as a carrier gas to improve signal sensitivity, reduce the mass discrimination and fractionation effects; mass fractionation significantly reduced by266nm femtosecond laser ablation relative to193nm excimer laser, mass fractionation induced by femtosecond laser is negligible; Tl fractionation factor used for Pb isotope mass fractionation correction according to the exponential law (taking into account the differences of the fractionation factors between Tl and Pb, optimize NIST SRM997Tl isotope ratios2.38890was uesd) to obtain accurate and precision Pb isotope ratios.Meanwhile, the first report of the USGS (GSE-1G, GSC-1G and GSA-1G) and CGSG series of reference material (CGSG-1, CGSG-2, CGSG-4and CGSG-5) Pb isotopic data by fLA-MC-ICP-MS analysis, the study results showed that the GSE-1G, GSC-1G, GSA-1G, CGSG-1, CGSG-2, CGSG-4and CGSG-5Pb isotopes in the range of100～200microns are homogeneous. 266nm femtosecond laser ablation-multicollector inductively coupled plasma mass spectrometry (fLA-MC-ICP-MS) analysis of Pb isotopic in plagioclase amphibolite rock from Qinling Group, Songshugou by in situ microanalysis, and gained1.00±0.17Ga Pb-Pb isochron age, the result show that the protolith of Qinling Group amphibolite have age1.00±0.17Ga, and the results agree with previous studies.4. Experiments for Fe isotope separation and purification procedures, carried out the solution nebulizer (SN) and membrane desolvation nebulizer (DSN)-multicollector inductively coupled plasma mass spectrometry (SN/DSN-MC-ICP-MS) Fe isotopic analysis instrument parameters and analytical methods research work;266nm femtosecond laser ablation-multicollector inductively coupled plasma mass spectrometry analysis technique (fLA-MC-ICP-MS) to explore in situ Fe isotope analysis in geological samples, study the experimental conditions, to establish Fe isotope fLA-MC-ICP-MS analysis method. Fe isotope composition in Songshugou dunite was analysis by fLA-MC-ICP-MS analytical techniques.Experiments to establish the the Fe isotope separation and purification procedures, the AG MP-1M anion exchange resin can be used for samples of Fe isotope separation and purification, and with the recovery more than99%, and also can be used for the separation and purification of Cu, Zn and Co.Instrument parameters and the experimental method were Carry out for sample solution (SN) and membrane to dissolve samples (DSN)-Multi-collector inductively coupled plasma mass spectrometry (SN/DSN-MC-ICP-MS) Fe isotopic analysis, more in-depth study the MC-ICP-MS analysis of ICP parameters (RF power, nebulizer gas flow), sampling mode, resolution, and analysis of test patterns on the impact of Fe isotope analysis, obtained857Fe and δ56Fe of IRMM-014are-0.006‰±0.012‰(2s) and0.002‰±0.022‰(2s), respectively, the results are consistent with the previous studies within2s the uncertainties. Long-term external precision of δ56Fe is0.02‰(2s). Hellium was also explored for trace gas addition for study the impact of it on Fe isotope analysis, the results shown that the addition of He gas can improve the precision of Fe isotope analysis. The established SN-MC-ICP-MS Fe isotopic analysis methods used for geological samples Fe isotope analysis.The femtosecond laser ablation266nm and multi-collector inductively coupled plasma mass spectrometry technique (fLA-MC-ICP-MS) were use to explore in situ microanalysis of Fe isotopes in the geological samples, experimental conditions, laser energy (or energy fluence), laser frequency and laser ablation spot beam were explored the impact on the Fe isotope in situ microanalysis. The initial Fe isotopes fLA-MC-ICP-MS analysis method were establishment, the Fe isotopic of IRMM-014are δ56Fe=-0.001±0.011%o (2s, n=52) and δ57Fe=-0.004±0.019%o (2s, n=52), respectively, the results are good consistent with the previous studies within2s the uncertainties; the obtained long-term external precision for δ56Fe was0.02‰(2s).Take Songshugou dunite for exemple, Fe isotope composition in olivine and chromite was analyzed using fLA-MC-ICP-MS technique.