| 1 | Accurate and precise determination of lead isotope composition in selected geochemical reference materials显示文摘Lead(Pb)isotopes have been extensively employed in tracing sources of Pb and its transport pathways through the environment.However,Pb isotopic ratios in related geochemical reference materials are scarce.Here,we report high-precision Pb isotopic ratios measured by Nu Plasma II MC-ICP-MS using calibrated ^(205)Tl/^(203)Tl=2.38865(NIST SRM 997)for mass discrimination correction.The long-term external precision(2SD)for NISTSRM 981 of Pb,BCR-2,and BHVO-2 are 0.31‰(n=105),0.42‰(n=11),and 0.25‰(n=5)for ^(208)Pb/ ^(206)Pb and 0.16‰,0.53‰,and 0.07‰for ^(206)Pb/ ^(207)Pb,both respectively,and their Pb isotopic ratios are in excellent agreement with the recommended values.Using this method,we report for the first time Pb isotopic compositions in shale SGR-1b(USGS);coal CLB-1(USGS);stream sediments GSD-17,-21,and-23(IGGE);soils GSS-12,-13,-14,-15,and-16(IGGE);plants GSV-1,-2,and-3(IGGE);and human hair GSH-1(IGGE). | Guangliang Wu Jian-Ming Zhu Decan Tan Guilin Han Lixing Zhang Kun Ren | 2017 | Acta Geochimica2017，36，3： | 3 |
| 2 | Optimizing the ratio of the spike to sample for isotope dilution analysis:a case study with selenium isotopes显示文摘Isotope dilution(ID)method has been widely applied to studies of elemental speciation and certification of the concentrations of geological reference materials.One of the key factors restricting the application of the ID method is the difficulty in identifying the optimal ratios of the isotope tracer(spike)to sample(S/N)and in estimating the error propagation.Here,using Se isotope as an example and employing a Monte Carlo method,we found that the optimal choice of spike and S/N are^(77)Se(spike)and 0.7,respectively.The S/N in the range from 0.1 to 4 can produce sufficiently low errors(<0.4%).Extending this method to other elements such as Cr,Fe,Ni,Sr,Cd and etc.,their optimal spike and S/N were also presented.According to the optimized parameters of Se,we determined the Se concentrations of geological reference materials(GRMs)by thiol cotton fiber(TCF)-hydride generation ID-MC-ICP-MS.The relative standard deviation is<5%,and the detection limit is reduced to0.1 ng/g.Most of the measured concentrations are consistent with those recommended by IGGE or reported previously.For some GRMs,discrepancies(e.g.6.90%for GSS-5)exist between our measurements and previous ones,which can be explained by the inhomogeneity of GRMs and/or the different digestion,purification and measurement methods among laboratories. | Decan Tan Wenpo Xu Zuochen Zhu Shehong Li Guangliang Wu Haibo Qin | 2020 | Acta Geochimica2020，39，2： | 0 |
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