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51.
Raphaelle Escoube Olivier J. Rouxel Béatrice Luais Emmanuel Ponzevera Olivier F.X. Donard 《Geostandards and Geoanalytical Research》2012,36(2):149-159
Recent analytical developments in germanium stable isotope determination by multicollector ICP‐MS have provided new perspectives for the use of Ge isotopes as geochemical tracers. Here, we report the germanium isotope composition of the NIST SRM 3120a elemental reference solution that has been calibrated relative to internal isotopic standard solutions used in the previous studies. We also intercalibrate several geological reference materials as well as geological and meteoritic samples using different techniques, including online hydride generation and a spray chamber for sample introduction to MC‐ICP‐MS, and different approaches for mass bias corrections such as sample–calibrator bracketing, external mass bias correction using Ga isotopes and double‐spike normalisation. All methods yielded relatively similar precisions at around 0.1‰ (2s) for δ74/70Ge values. Using igneous and mantle‐derived rocks, the bulk silicate Earth (BSE) δ74/70Ge value was re‐evaluated to be 0.59 ± 0.18‰ (2s) relative to NIST SRM 3120a. Several sulfide samples were also analysed and yielded very negative values, down to ?4.3‰, consistent with recent theoretical study of Ge isotope fractionation. The strong heavy isotope depletion in ore deposits also contrasts with the generally positive Ge isotope values found in many modern and ancient marine sediments. 相似文献
52.
Martin Oeser Stefan Weyer Ingo Horn Stephan Schuth 《Geostandards and Geoanalytical Research》2014,38(3):311-328
In this study, a technique for high precision in situ Fe and Mg isotope determinations by femtosecond‐laser ablation‐multi collector‐ICP‐MS (fs‐LA‐MC‐ICP‐MS) was developed. This technique was employed to determine reference values for a series of common reference glasses that may be used for external standardisation of in situ Fe and Mg isotope determinations in silicates. The analysed glasses are part of the MPI‐DING and United States Geological Survey (USGS) reference glass series, consisting of basaltic (BIR‐1G, BCR‐2G, BHVO‐2G, KL2‐G, ML3B‐G) and komatiitic (GOR128‐G and GOR132‐G) compositions. Their Fe and Mg isotope compositions were determined by in situ fs‐LA‐MC‐ICP‐MS and by conventional solution nebulisation multi‐collector ICP‐MS. We determined δ56Fe values for these glasses ranging between ‐0.04‰ and 0.10‰ (relative to IRMM‐014) and δ26Mg values ranging between ‐0.40‰ and ‐0.15‰ (relative to DSM‐3). Our fs‐LA‐MC‐ICP‐MS results for both Fe and Mg isotope compositions agreed with solution nebulisation analyses within analytical uncertainties. Furthermore, the results of three USGS reference glasses (BIR‐1G, BHVO‐2G and BCR‐2G) agreed with previous results for powdered and dissolved aliquots of the same reference materials. Measurement reproducibilities of the in situ determinations of δ56Fe and δ26Mg values were usually better than 0.12‰ and 0.13‰ (2s), respectively. We further demonstrate that our technique is a suitable tool to resolve isotopic zoning in chemically‐zoned olivine crystals. It may be used for a variety of different applications on isotopically‐zoned minerals, e.g., in magmatic or metamorphic rocks or meteorites, to unravel their formation or cooling rates. 相似文献
53.
Geological reference materials (RMs) with variable compositions and NIST SRM 612 were analysed by isotope dilution mass spectrometry for bulk rock concentrations of chalcogen elements (sulfur, selenium and tellurium), rhenium and platinum‐group elements (PGEs: Ru, Pd, Os, Ir and Pt), including the isotope amount ratios of 187Os/188Os. All concentrations were obtained from the same aliquot after HCl‐HNO3 digestion in a high pressure asher at 320 °C. Concentrations were determined after chemical separation by negative TIMS, ICP‐MS and hydride generation ICP‐MS (Se, Te). As in previous studies, concentrations of the PGEs in most RMs were found to be highly variable, which may be ascribed to sample heterogeneity at the < 1 g level. In contrast, S, Se and Te displayed good precision (RSD < 5%) in most RMs, suggesting that part of the PGE budget is controlled by different phases, compared with the chalcogen budget. The method may minimise losses of volatile chalcogens during the closed‐system digestion and indicates the different extent of heterogeneity of chalcogens, Re and PGEs in the same sample aliquot. OKUM, SCo‐1, MRG‐1, DR‐N and MAG‐1 are useful RMs for the chalcogens. NIST SRM 612 displays homogenous distribution of S, Se, Te, Pt and Pd in 30 mg aliquots, in contrast with micro‐scale heterogeneity of Se, Pd and Pt. 相似文献
54.
Xian-Hua Li Weng-Guo Long Qiu-Li Li Yu Liu Yong-Fei Zheng Yue-Heng Yang Kevin R. Chamberlain De-Fang Wan Cun-Hua Guo Xuan-Ce Wang Hua Tao 《Geostandards and Geoanalytical Research》2010,34(2):117-134
We introduce a potential new working reference material – natural zircon megacrysts from an Early Pliocene alkaline basalt (from Penglai, northern Hainan Island, southern China) – for the microbeam determination of O and Hf isotopes, and U–Pb age dating. The Penglai zircon megacrysts were found to be fairly homogeneous in Hf and O isotopes based on large numbers of measurements by LA-multiple collector (MC)-ICP-MS and SIMS, respectively. Precise determinations of O isotopes by isotope ratio mass spectrometry (IRMS) and Hf isotopes by solution MC-ICP-MS were in good agreement with the statistical mean of microbeam measurements. The mean δ18O value of 5.31 ± 0.10‰ (2s) by IRMS and the mean 176Hf/177Hf value of 0.282906 ± 0.0000010 (2s) by solution MC-ICP-MS are the best reference values for the Penglai zircons. SIMS and isotope dilution-TIMS measurements yielded consistent 206Pb/238U ages within analytical uncertainties, and the preferred 206Pb/238U age was found to be 4.4 ± 0.1 Ma (95% confidence interval). The young age and variably high common Pb content make the Penglai zircons unsuitable as a primary U–Pb age reference material for calibration of unknown samples by microbeam analysis; however, they can be used as a secondary working reference material for quality control of U–Pb age determination for young (particularly < 10 Ma) zircon samples. 相似文献
55.
Stephen F. Crowley 《Geostandards and Geoanalytical Research》2010,34(2):193-206
International carbon and oxygen isotope calibration material NBS 19 and reference materials NBS 18, International Atomic Energy Agency (IAEA)-CO-1 and IAEA-CO-8 are prepared from naturally occurring rock specimens of marble and carbonatite. Mineralogical and chemical analysis showed that only NBS 19 and IAEA-CO-1 represent essentially pure samples of calcite containing < and minimal (< 1%) quantities of quartz. In contrast, both NBS 18 and IAEA-CO-8, although primarily composed of calcite, are contaminated by a range of additional phases. NBS 18 was estimated to contain 1% Fe-dolomite and trace (< 1%) quantities of apatite and quartz. IAEA-CO-8 was estimated to contain at least 4% non-carbonate material (including apatite, barite, biotite and magnetite). NBS 18 and IAEA-CO-8 are both derived from samples of carbonatite and the calcite component of each material is characterised by appreciable substitution of Mg + Mn + Sr ± Fe ± Ba (Σ ≈ 14000–15000 μg g-1) for Ca. The observations reported in this study complement data in the literature detailing significant grain-scale isotopic heterogeneity in NBS 18 and IAEA-CO-8. Both data sets highlight the need for careful characterisation of calibration materials prior to distribution. 相似文献
56.
B. Batjargal B. Davaasuren D. Erdenetsetseg 《Geostandards and Geoanalytical Research》2010,34(3):231-236
This paper briefly outlines the production and certification of reference materials at the Central Geological Laboratory (CGL) of Mongolia. The marketing of CRMs produced in Mongolia, as well as problems encountered in internationally recognised certification attempts and some proposed solutions, are discussed. The basic elements of the CGL’s strategy for the development of the CRM sector are to produce high quality CRMs according to the requirements of internationally recognised norms, to consider the market needs, to certify the RMs at the international level and to widely advertise them to the geochemical community. The CGL has already established the basis for the further development of this sector by, for instance, accreditation under ISO/IEC 17025, by modernising its preparation technology, by cooperation with international organisations in the field of CRMs and by permanent participation in the International Association of Geoanalysts’ GeoPT™ proficiency testing programme. 相似文献
57.
Anastassia Y. Borisova Rémi Freydier Mireille Polvé Klaus Peter Jochum Frederic Candaudap 《Geostandards and Geoanalytical Research》2010,34(3):245-255
This paper reports on the application of variants of LA-ICP-MS – including infrared femtosecond laser ablation (fs-LA) inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS) and nanosecond laser ablation (ns-LA) coupled with single-collector sector-field (SF-) ICP-MS – to the in situ determination of trace elements in different splits of the reference material (RM) ATHO-G (MPI-DING). Analyses of the materials performed by fs- and ns-LA-ICP-MS demonstrated the efficiency of the techniques with typical accuracy at a level of ≤ ± 20%. One ‘anomalous’ split, however, displayed a significant discrepancy from the reference concentrations for B, V, Zn, Mo, Sn, Sb, Cs, W and Pb. Three- to six-fold enrichment of V, Mo, Cs and Pt relative to the reference contents in this split is likely to have been due to direct contact of the silicate melt with Pt crucible walls and ceramics. Boron, Zn, Sn, Sb, W and Pb depletion relative to the reference concentrations is probably due to siderophile element adsorption by the Pt walls and/or related to the formation of volatile-depleted compositional cords during the preparation process. Our results imply that additional precautions should be taken against volatile/siderophile element heterogeneity in marginal/surface layers (≤ 10 mm) during the preparation of RMs by the fusion technique. 相似文献
58.
Catherine Guerrot Romain Millot Michèle Robert Philippe Négrel 《Geostandards and Geoanalytical Research》2011,35(2):275-284
We report an approach for the accurate and reproducible measurement of boron isotope ratios in natural waters using an MC‐ICP‐MS (Neptune) after wet chemistry sample purification. The sample matrix can induce a drastic shift in the isotopic ratio by changing the mass bias. It is shown that, if no purification is carried out, the direct measurement of a seawater diluted one hundred times will induce an offset of ?7‰ in the isotopic ratio, and that, for the same concentration, the greater the atomic mass of the matrix element, the greater the bias induced. Whatever the sample, it is thus necessary to remove the matrix. We propose a method adapted to water samples allowing purification of 100 ng of boron with a direct recovery of boron in 2 ml of 3% v/v HNO3, which was our working solution. Boron from the International Atomic Energy Agency IAEA‐B1 seawater reference material and from the two groundwater reference materials IAEA‐B2 and IAEA‐B3, was chemically purified, as well as boron from the certified reference material NIST SRM 951 as a test. The reproducibility of the whole procedure (wet chemistry and MC‐ICP‐MS measurement) was ± 0.4‰ (2s). Accuracy was verified by comparison with positive‐TIMS values and with recommended values. Seawater, being homogeneous for boron isotope ratios, is presently the only natural water material that is commonly analysed for testing accuracy worldwide. We propose that the three IAEA natural waters could be used as reference samples for boron isotopes, allowing a better knowledge of their isotopic ratios, thus contributing to the certification of methods and improving the quality of the boron isotopic ratio measurements for all laboratories. 相似文献
59.
Bleuenn Gueguen Olivier Rouxel Emmanuel Ponzevera Andrey Bekker Yves Fouquet 《Geostandards and Geoanalytical Research》2013,37(3):297-317
Although initial studies have demonstrated the applicability of Ni isotopes for cosmochemistry and as a potential biosignature, the Ni isotope composition of terrestrial igneous and sedimentary rocks, and ore deposits remains poorly known. Our contribution is fourfold: (a) to detail an analytical procedure for Ni isotope determination, (b) to determine the Ni isotope composition of various geological reference materials, (c) to assess the isotope composition of the Bulk Silicate Earth relative to the Ni isotope reference material NIST SRM 986 and (d) to report the range of mass‐dependent Ni isotope fractionations in magmatic rocks and ore deposits. After purification through a two‐stage chromatography procedure, Ni isotope ratios were measured by MC‐ICP‐MS and were corrected for instrumental mass bias using a double‐spike correction method. Measurement precision (two standard error of the mean) was between 0.02 and 0.04‰, and intermediate measurement precision for NIST SRM 986 was 0.05‰ (2s). Igneous‐ and mantle‐derived rocks displayed a restricted range of δ60/58Ni values between ?0.13 and +0.16‰, suggesting an average BSE composition of +0.05‰. Manganese nodules (Nod A1; P1), shale (SDO‐1), coal (CLB‐1) and a metal‐contaminated soil (NIST SRM 2711) showed positive values ranging between +0.14 and +1.06‰, whereas komatiite‐hosted Ni‐rich sulfides varied from ?0.10 to ?1.03‰. 相似文献
60.
Fabiano R. L. Faulstich Reiner Neumann Jacques Pironon Aurelien Randi 《Geostandards and Geoanalytical Research》2013,37(4):393-402
In this study, we detail procedures to synthesise inclusions of fluids of known composition under diagenetic conditions – low temperatures (50–180 °C) and pressures (2–25 MPa) – hosted by quartz. Pre‐existing microcavities in polished quartz chips were used, decrepitated and rinsed before being healed in an autoclave. Each synthesis required around 4 weeks. A range of biphase liquid–vapour inclusions in the H2O–CH4–NaCl system, similar to natural ones, were synthesised in quartz, varying the content of all three components. The quartz chips were checked before and after synthesis by optical microscopy, microthermometry and Raman spectroscopy. The method was used to build a series of calibration curves relating methane‐to‐water count ratios to the methane content of aqueous fluid inclusions. Good correlation was obtained between Raman band area ratios and the expected CH4 solubilities from equations of state. The chosen procedure's main advantages, compared with other published methods, are as follows: quicker healing of the microfractures at lower temperatures, larger inclusions, simple quartz sample preparation, control of fluid inclusion composition and the use of commercial reactors. Such reference material inclusions allow the calibration of Raman microspectrometers with the objective of PTX reconstruction of palaeofluid migration in petroleum reservoirs. 相似文献