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This study compares three zircon synthesis techniques (synthesis, high-temperature and high-pressure sintering and fast hot-pressing sintering) for the preparation of reference materials for Hf isotope analysis of zircon by laser ablation multi-collector inductively-coupled plasma mass spectrometry (LA-MC-ICP-MS). Ultrafine milled zircon powder particles doped with Yb2O3 produced by wet milling were used to synthesize zircon samples by using high-temperature and high-pressure sintering and fast hot-pressing sintering techniques. Li–Mo flux was necessary to obtain synthetic zircon grains. Zr signals for synthetic zircon grains and high-temperature and high-pressure sintered zircon are consistent with those of natural zircons but higher than that of fast hot-pressing sintered zircon, indicating that high-temperature and high-pressure sintered zircon has approximated the theoretical maximum density due to high pressure. The Hf isotopic compositions of high-temperature and high-pressure sintered and fast hot-pressing sintered zircon are comparable to those of the initial starting materials, whereas the Hf isotopes in synthetic zircon grains deviate slightly from those of the initial Hf solution. Compared with Hf isotope ratios obtained by SN-MC-ICP-MS, all preparation techniques give reliable LA-MC-ICP-MS results, suggesting that all synthetic zircon samples have great potential as both tools for in situ method development and isotopic reference materials. [ABSTRACT FROM AUTHOR]

Sulfur isotopes are important tracers in various geochemical processes. A matrix-matched reference material is essential for in situ sulfur isotope ratio measurement in sphalerite (ZnS), an abundant zinc sulfide in base metal deposits. In this study, natural sphalerite powders (GBW07270) were ground into ultra-fine powders and then sintered by using a plasma-activated sintering (PAS) method at 1000 °C and 50 MPa for 10 minutes. The synthesized sphalerite has a smooth surface and dense structure, making it suitable for laser ablation analysis. To investigate whether the PAS-synthesized sphalerite is an appropriate matrix-matched reference material for in situ sulfur isotope determination, a large number of in situ S isotope measurements were performed on the PAS-synthesized sphalerite by laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). The LA-MC-ICP-MS results are highly consistent and yield a mean δ34SV-CDT value of −5.44 ± 0.20‰ (2SD, n = 1008), which agrees well with that measured by gas source isotope ratio mass spectrometry (GS-IRMS). Therefore, the PAS-synthesized sphalerite has a homogeneous sulfur isotopic composition and is a suitable matrix-matched reference material available for in situ S isotope measurements of sphalerite. [ABSTRACT FROM AUTHOR]

High-quality Sr isotope data are critically dependent on the quality of reference materials that are used for instrumental calibration and data monitoring during laser ablation (LA) multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) analysis. We have prepared a new natural calcite reference material MNP for in situ Sr isotope measurement by LA-MC-ICP-MS. Detailed textural examination and major element determination suggest that the MNP calcite reference material has no growth rim or zoning. Trace element analyses by LA-ICP-MS showed that the MNP calcite reference material has low Rb/Sr ratios, low amounts of heavy rare earth elements (HREEs) and high Sr contents. The MNP calcite reference material is homogeneous with respect to Sr isotopes based on a large number of measurements performed by single-grain solution nebulizer (SN)-MC-ICP-MS and LA-MC-ICP-MS. The traditional bulk isotope analyses by TIMS and SN-MC-ICP-MS yielded a mean 87Sr/86Sr ratio of 0.70617 ± 0.00005(2SD, n = 18). A total of 585 LA-MC-ICP-MS Sr isotope analyses on random calcite crystals show homogeneous Sr isotopic compositions with an average 87Sr/86Sr ratio of 0.70617 ± 0.00005 (2SD), identical with the solution-based data. These suggest that MNP calcite can be used as a potential reference material for microbeam Sr isotopic analysis. [ABSTRACT FROM AUTHOR]

Microanalysis of tin isotopes in cassiterite by laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) has been an important tool to reconstruct the fluid evolution or discriminate petrological sources and processes. However, it is a major challenge to prepare the absolutely essential cassiterite reference material that has a homogeneous Sn isotope composition on a micron scale. In this study, we report a novel method to synthesize a homogeneous cassiterite reference material via sintering a micrometer powder. Under the optimized conditions (600 °C, 1 GPa), the synthesized cassiterite has a smooth surface and dense structure that is suitable for laser ablation analysis. The Sn signal for the synthesized cassiterite was consistent with that of natural cassiterite and lower than that of the pressed powder pellets by LA-ICP-MS, indicating that the sintered cassiterite approximated the theoretical maximal density. LA-MC-ICP-MS measurements suggest that the homogeneity (2SD) for δ124Sn/120Sn was improved from 0.64‰ (original cassiterite crystal) to 0.10‰ (synthesized cassiterite). The reproducibility of δ124Sn/120Sn was 0.07‰ (2SD) for the synthesized cassiterite. These data have demonstrated that the synthesized cassiterite has a homogeneous distribution of Sn isotopes. Therefore, we recommend combining ultra-fine powders with the high-temperature sintering technique to synthesize other minerals for microanalysis. [ABSTRACT FROM AUTHOR]

This study presents a practical method for high-precision Fe isotope determination without column chromatography purification for iron-dominated mineral samples using multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). A series of comparable experiments (with or without column chromatography) were performed to evaluate whether non-deviated Fe isotope ratios can be obtained directly by MC-ICP-MS using standard-sample bracketing (SSB) without column chromatography purification. Forty iron-dominated material/mineral samples (pure iron wire, pyrite, chalcopyrite, magnetite, hematite, siderite, goethite, pyrrhotite, arsenopyrite, specularite, ilmenite, limonite, lollingite, ilvaite, and Fe–Mn nodule) were investigated, and the results showed little bias in δ56Fe values compared with those of mineral materials via column chromatography purification, with Δδ56Fewithout–with ranging from −0.06‰ to +0.06‰. This means that Fe isotope ratios in Fe-dominated minerals can be achieved without column chromatography, due to the simple matrix and the stability of the machine by using the SSB method in high resolution wet plasma mode. The concentration effect and nitric acidity mismatch effects, as well as the matrix effect, were strictly assessed by MC-ICP-MS in high resolution wet plasma mode. Finally, a long-term reproducibility of better than ± 0.05‰ (n = 123, 2 sd) was achieved by repeatedly measuring pyrite without column chromatography over 6 months. Compared with the column chromatography purification method, the without column chromatography method significantly simplifies the chemical procedure and improves the efficiency of iron-dominated mineral Fe isotope analysis. [ABSTRACT FROM AUTHOR]

Sulfur isotopes are important geochemical tracers in the diverse fields of geosciences. Controlling the accuracy and precision of the microanalysis of sulfur isotopes requires well-characterized reference materials with matrices similar to those of unknown samples. This study introduces a new natural chalcopyrite reference material, TC1725, for S isotope analysis by laser ablation multiple-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). The chalcopyrite grain is homogeneous with respect to S isotopes based on a large number of measurements by LA-MC-ICP-MS and solution nebulizer (SN)-MC-ICP-MS. Isotope ratio mass spectrometry (IRMS) for S isotopic analysis produced a mean δ34SVCDT value of +12.78 ± 0.16‰ (2 s, n = 11). Results of SN-MC-ICP-MS and LA-ICP-MS analyses are consistent with the IRMS ratios within the uncertainty. A total of 981 sulfur isotope ratio spot measurements conducted on the cruciform sections and randomly selected chalcopyrite grains of TC1725 by LA-MC-ICP-MS yielded highly consistent sulfur isotope ratios. [ABSTRACT FROM AUTHOR]

A new simple and rapid method was developed for the purification of Mg from carbonate samples, especially for calcite-rich carbonates. The proposed separation protocol consists of only two types of eluents (4 mol l−1 HNO3 and deionized water) based on 2 ml of DGA resin. 4 ml of HNO3 can effectively separate Mg from calcite-rich carbonates with a high yield within one hour. The Mg elution curve would not drift with different Mg and Ca loading onto the DGA resin. Ca/Mg ratios of the purified samples could be reduced by five orders of magnitude compared to the unpurified calcite-rich carbonate samples. The precision and accuracy of this new method have been evaluated by measurements of the synthetic solution, carbonate standard material, and ten readily available Chinese carbonate reference materials. All the Mg isotopic analytical results were, within analytical uncertainties, essentially identical with the data published previously. Therefore, the new method can be a great option for purifying Mg from carbonate samples for isotopic analysis. [ABSTRACT FROM AUTHOR]

Natural water evaporation is a ubiquitous resource at the Earth's surface. Actuating materials that convert such evaporation energy into mechanical motions are highly desirable but challenging. Herein, tough nacre-mimetic films featuring excellent dry/wet tensile strength (294.4 MPa/182.3 MPa) are reported. Benefiting from this feature, the resultant film actuators can not only perform fast flipping motion and lasting oscillation driven by natural evaporation, but also undergo rapid turnover upon exposure to small humidity gradients on the palm of the hand. Importantly, the film actuators further exhibit exceptional actuation without fatigue when exposed to thermal water vapors. Furthermore, it is demonstrated that the stretch-induced oriented film could be used to construct a self-powered soft robot driven by water gradients. As a proof of concept, a natural evaporation-driven generator is assembled by connecting the actuators with a piezoelectric element to power a LED. These demonstrations clearly show that the biomimetic films are promising for harnessing natural evaporation to drive various self-powered devices. [ABSTRACT FROM AUTHOR]

We have prepared a large volume of pure, concentrated and homogeneous magnesium standard solution (GSB-Mg) to be used as a secondary reference standard by the magnesium isotope community. This new standard solution can also be used for quality assurance, including the development and validation of analytical procedures, preparation and test of analytical methods, quality control and training of analysts. The δ26Mg values relative to DSM3, measured by multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), are −2.038 ± 0.027‰ (n = 45, Lab 1), −2.024 ± 0.055‰ (n = 7, Lab 2), −2.078 ± 0.081‰ (n = 6, Lab 3), −2.037 ± 0.015‰ (n = 8, Lab 4), and −2.067 ± 0.039‰ (n = 12, Lab 5). The δ26Mg and δ25Mg values for the GSB-Mg standard solution are −2.049‰ and −1.056‰, with a combined expanded (k = 2) uncertainty of 0.049‰ and 0.028‰, respectively. These values show higher similarity to Mg isotopic compositions of carbonates and marine sediments compared to those of the mantle and crustal rocks, making the GSB-Mg solution a great reference material for Mg isotopic analysis of carbonates and marine sediments. [ABSTRACT FROM AUTHOR]

This study presents a practical method for high-precision Mg isotope determination without column chromatography for carbonate samples using sulphuric acid and MC-ICP-MS. The protocol uses the chemical reaction between carbonates and sulphuric acid to generate a CaSO4 precipitate and MgSO4 supernatant, which are used to determine Mg isotopic ratios. The matrix effects and the sulphuric acid conditions were rigorously examined using a Nu Plasma II in wet plasma mode. The precision and accuracy of this method were tested by measurements of the carbonite standard material JDo-1 over four months. The δ26Mg of JDo-1 is −2.32 ± 0.11‰ (2SD, n = 34) relative to DSM3, well consistent with the recommended value (−2.35 ± 0.15‰). The robustness of this method was further assessed by replicated analyses of ten Chinese carbonate reference materials that covered a large range of MgO contents from 5.98 wt% to 20.91 wt%. [ABSTRACT FROM AUTHOR]

In this work, we improved the sensitivity of a multi-collector-inductively coupled plasma mass spectrometry system by increasing the vacuum of the expansion chamber using a high-speed EH mechanical booster pump (EH500, 500 m3 h−1, BOC Edwards) in conjunction with a standard E2M80 pump (80 m3 h−1, BOC Edwards). The vacuum was improved from 1.0 mbar to less than 0.5 mbar. The sample ion yield for heavy isotopes, such as those of Pb, was improved from 0.047% to 0.072% in the wet-plasma mode (sample uptake rate, 113 μL min−1), and from 1.35% to 1.84% in the dry-plasma mode (sample uptake rate 105 μL min−1); the variation in the background intensity was less than 1.3 mV for all the Faraday cups. Thus, the sample ion yield in the wet-plasma mode was enhanced more effectively than that in the dry-plasma mode owing to a slightly larger orifice in the wet cone setup. The accuracies for all the isotopes tested, including those of non-traditional metal ones, in both modes were identical to previously published data within an error of 2 s. These results indicate that improving the vacuum at the interface has no effect on the accuracy of isotope measurements and is an effective method for improving the detectability of isotopic compositions for bulk solution analysis with low element contents and the spatial resolution for measurements performed using the laser-ablation sampling technique. This work could provide an alternative for laboratories with a similar device, when tackling samples with low contents. [ABSTRACT FROM AUTHOR]

This study presents a chemical protocol for the separation of Mg that is particularly adapted for diverse igneous rock samples, especially for high-K and low-Mg rocks. This protocol is based on a combination of three procedures: the removal of K from the samples using the precipitation procedure, followed by the separation of Fe and Ca using 2 mL of AG50W-X12 cation exchange resin, and finally the removal of Al, Ti, Na, and Fe elements using 0.5 mL of AG50W-X12 cation exchange resin. The effect of acidity and concentration mismatch as well as the matrix effect were rigorously evaluated using Nu Plasma II MC-ICP-MS with a wet plasma mode. The δ26Mg mean values of the GSB and Alfa Mg standard solutions are −2.05 ± 0.05‰ (2 standard deviation (2s), n = 106) and −3.91 ± 0.04‰ (2s, n = 51), respectively, which serve as in-house Mg standards in the State Key Laboratory of Continental Dynamics (SKLCD). The average δ26Mg value of one multi-elemental Mg standard GSB-1, made by adopting GSB with matrix elements, agrees well with the recommended value after precipitation and chromatographic separation. The long-term reproducibility, assessed by repeated measurements of Mg standard solutions and reference materials (RMs), is ±0.06‰. The robustness of our method is further assessed by the replicated analyses of fifteen rock standards and olivine grains with large variations in MgO and K2O content. [ABSTRACT FROM AUTHOR]

In this study, Pb isotope ratios in ferromanganese nodules were determined with good repeatability and minimum laboratory bias using laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). One certified ferromanganese nodule reference material, NOD-A-1, in the form of pressed powder pellets (PPPs) produced upon ultrafine processing, was homogeneous enough to be used as an in-house matrix-matched standard or quality control sample for Pb isotopic microanalysis. The Tl normalization exponential law correction method with CTl-NIST SRM 997/CTl-sample≥ 15 (method 1) and the standard-sample-bracketing (SSB) method (method 2) were utilized to determine Pb isotope ratios with good repeatability and laboratory bias. In situ measurements of the Pb isotopes yielded a good relative standard deviation (2RSD) of ＜0.036% for 207,208Pb/206Pb and ＜0.066% for 206,207,208Pb/204Pb. In addition, the matrix effect was insignificant when the silicate glass reference material was employed as the external standard in the ferromanganese nodules using these two methods, resulting in relative errors (RE) of ＜0.064% for 206,207,208Pb/204Pb, and ＜0.046% for 207,208Pb/206Pb. The in situ Pb isotopic compositions of three Chinese ferromanganese nodules, GBW07249, GBW07295, and GBW07296, were in good agreement with those obtained by solution nebulization MC-ICP-MS (SN-MC-ICP-MS) within 2s (standard deviation) measurement uncertainties, demonstrating the reliability and robustness of our proposed analytical protocol. [ABSTRACT FROM AUTHOR]

We prepared a series of pressed powder tablets and chalcopyrite glass standards to correct mass bias when using standard–sample bracketing for in situ sulfur isotope measurements. A femtosecond laser ablation coupled multi-collector inductively coupled plasma mass spectrometry (fsLA-MC-ICP-MS) method was used to determine the sulfur isotope composition of these standards. Chalcopyrite glass (YN411-m) was prepared by quickly quenching the fused chalcopyrite, which was melted at 1000 °C under a protective N2 atmosphere. Multiple experiments were conducted for homogeneity testing of YN411-m by fsLA-MC-ICP-MS and the external precision was 0.28‰ (n = 35). Mineral particles, pressed powder tablets, and chalcopyrite glass were used as bracketing standards when determining the δ34S of a natural chalcopyrite (GC). The results showed that the concentration, elemental composition, and crystal structure caused the matrix effect. Considering practicability, the melted glass was a more appropriate standard than the pressed powder tablet. We also found that the carrier gas flow rate, laser fluence, and spot size impacted the regularity of results. Therefore, we can obtain accurate δ34S by adjusting the laser and MC-ICP-MS parameters when using non-matrix matching standards. Furthermore, fsLA-MC-ICP-MS is advantageous for in situ sulfur isotope measurement because the sensitivity can be improved and it dramatically improves the spatial resolution (10–20 μm), which can be used to explain the origin of multi-genesis deposits by analyzing smaller mineral micro-areas, especially mineral fracture-filling sulfides later in mineralization. [ABSTRACT FROM AUTHOR]

In this study, we present a new method for the dissolution of silicate rocks by flux-free fusion using a boron nitride vessel in preparation for analysis of bulk rock trace elements; this method is especially applicable to felsic intrusive rocks. The method was evaluated by analyzing five intrusive rocks (GSP-2, GSP-1, G-2, GSR-1 and QLO-1) and five extrusive rocks (AGV-2, BCR-2, BHVO-2, GSR-3 and RGM-2). The optimum conditions for the fusion of intrusive rocks were determined to be heating at 1600 °C for 1 min, which is effective to break up strong Si–O bonds. The fused glasses were dissolved using HF/HNO3 acids in closed screw-top Savillex vials on a hotplate; no high-pressure PTFE digestion bomb was required. Zr and Hf were completely recovered from the granodiorite GSP-2 reference material in 6 hours at 150 °C, which was 8 times faster than the method using a conventional high-pressure PTFE digestion bomb at 190 °C. The precision (RSD%, 1 s) of the elemental determinations in nearly 92% of the analyzed samples was better than 4%. Replicate analyses (n = 3) of the reference materials indicated that most of the results agreed with the reference values within a relative error of ＜10%. Additionally, the flux-free fusion retained all the materials in solution and was valid for volatile elements. [ABSTRACT FROM AUTHOR]