Geostandards and Geoanalytical Research最新文献

The mass fractions of Cl and Br in melt, fluid and mineral phases are crucial for tracing geological processes, exploring ore deposits and assessing environmental impacts of volcanic halogen degassing. However, the scarcity of well-characterised reference materials for in situ Cl and Br measurement remains a significant challenge. Here, a suite of gem-quality scapolite samples from world-wide was characterised by laser ablation ICP-MS, electron probe microanalysis (EPMA) and instrumental neutron activation analysis (INAA). The results revealed reproducible mass fractions in scapolite samples TSNY (3.63 ± 0.13% m/m Cl; 319 ± 12 μg g^-1 Br), MDJ (3.01 ± 0.20% m/m Cl; 225 ± 16 μg g^-1 Br), and BX (2.76 ± 0.07% m/m Cl; 251 ± 15 μg g^-1 Br), which were identified as optimal calibration materials across a broad range of Br mass fractions. Additionally, samples SM (2.76 ± 0.13% m/m Cl; 1186 ± 146 μg g^-1 Br), AFH (3.92 ± 0.14% m/m Cl; 44 ± 3 μg g^-1 Br), and XJ (3.82 ± 0.10% m/m Cl; 42 ± 3 μg g^-1 Br) served as effective secondary reference materials for quality monitoring purposes. Ablations were conducted with a 90 μm spot size, 5 Hz repetition rate and 100 ms dwell time, with ³⁵Cl and ⁸¹Br identified as the preferred isotopes for accurate Cl-Br quantification. The scapolite samples demonstrated excellent calibration performance, with 2 RSD and bias values between 6 to 7% and 0.8 to 1.6%. This work provides a reliable set of reference materials for Cl-Br measurement, enhancing the precision and accuracy of LA-ICP-MS in geological research.

This chapter (Nano-Imaging for Advanced X-ray Fluorescence and Absorption Spectroscopy Applications) is a contribution to the Geostandards and Geoanalytical Research Handbook of Rock and Mineral Analysis – an online textbook that is a fully revised and updated edition of A Handbook of Silicate Rock Analysis (P. J. Potts, 1987, Blackie, Glasgow).

Chapter 16 (from Section 3 of the handbook devoted to microbeam techniques) has been designed to provide a coherent progression, starting with a brief introduction of the essential fundamentals and the practical information needed to understand the experimental specifics of nano-XRF imaging. This concise yet crucial information is followed by a comprehensive presentation of current applications of nano-XRF imaging, with examples showcasing elemental measurement and XAS applications based on nano-XRF imaging. To conclude, the final section offers a brief overview of emerging perspectives that should be of particular interest to young researchers at the beginning of their careers.

The geochemistry of lithium and boron isotopes is widely applied to a variety of Earth science disciplines. In situ measurement of Li and B isotope ratios requires matrix-matched reference materials for calibration, method validation and inter-laboratory data comparison. In this study, we characterise the Li and B isotope ratios (δ⁷Li and δ¹¹B) of the seven glass reference materials OJY-1, OH-1, OA-1, CGSG-1, CGSG-2, CGSG-4 and CGSG-5. These seven materials exhibit relative homogeneous δ⁷Li and δ¹¹B values at the spatial resolution of 10–120 μm, as revealed by multiple spot analyses using LA-MC-ICP-MS (n = 80–100) and SIMS (n = 8–12) on different grains. The 2s of δ⁷Li and δ¹¹B in these materials as determined by LA-MC-ICP-MS and SIMS ranges from ~ 0.40 to ~ 1.50‰. The recommended δ⁷Li and δ¹¹B values were determined using solution MC-ICP-MS techniques, and data from independent laboratories showed high precision with discrepancies within ~ 1.50‰. The Li and B mass fractions of the various glasses differ, ranging from ~ 40 μg g^-1 to 2000 μg g^-1 and ~ 40 μg g^-1 to 5000 μg g^-1, respectively. The various glasses also have different δ⁷Li and δ¹¹B values, ranging from +0.99 to +5.69‰ and -10.92 to +0.25‰, respectively. Notably, OA-1 and OH-1 are high-silica glasses (SiO₂ > 75% m/m) and, therefore, may be particularly helpful for Li and B isotope analysis of highly evolved magmatic rocks. These investigated glasses have great potential as reference materials for the in situ measurement of Li and B isotope ratios.

This chapter (Laser Ablation-ICP-MS for the In Situ Analysis of Geological Samples) is a contribution to the Geostandards and Geoanalytical Research Handbook of Rock and Mineral Analysis – an online textbook that is a fully revised and updated edition of A Handbook of Silicate Rock Analysis (P. J. Potts, 1987, Blackie, Glasgow).

This Chapter (from Section 3 of the handbook dealing with microbeam analytical techniques) presents an overview of fundamental aspects of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and its application relevant to multi-element measurement and U-Pb dating of geological samples. The chapter describes instrumentation currently used for LA-ICP-MS, physical processes that occur at the ablation site, during aerosol transport and in the ICP, and approaches to quantification of LA-ICP-MS data. Description of laser ablation microprobes focuses on their design aspects that affect analytical performance such as the source of laser light, configuration of the optical path of the laser beam, and the design of the sample cell. Description of ICP-MS instruments focuses on the implications of using single collector mass spectrometers, which are currently the most common type of ICP-MS instruments used for LA-ICP-MS. Description of the tubing connecting laser microprobes to ICP-MS instruments focuses on the impact of its configuration on the uncertainty of LA-ICP-MS measurement results. The description of physical processes includes aspects of the ablation process, digestion of laser ablation aerosol in a dry ICP, and down-hole fractionation during ablation at a fixed location on the sample. Description of approaches to quantification of LA-ICP-MS data covers internal standardisation, calibration of ICP-MS instrument response during analytical runs, matrix effects, use of secondary reference material, interferences and memory effects.

In this work, we describe a measurement procedure that provides high precision measurement results of samarium (Sm) and neodymium (Nd) mass fractions, as well as ¹⁴³Nd/¹⁴⁴Nd ratios in mafic–ultramafic rock reference materials, using isotope dilution (ID) multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). This technique is superior in terms of intermediate measurement precision, simplicity and rapidity compared with thermal ionisation mass spectrometry (TIMS) based on high-sensitivity NdO⁺ techniques. Samples were spiked with a ¹⁴⁹Sm-¹⁵⁰Nd enriched tracer and then digested using a commonly used protocol involving HF, HNO₃ and HClO₄. The sample solution was directly purified using a single DGA resin column to obtain Sm and Nd fractions with high purity and recovery. The samples including five serpentinised dunites (DZE-1, DZE-2, NIM-D, JP-1, DTS-2b), a harzburgite (HARZ01), a serpentinised harzburgite (MUH-1; certified reference material according to ISO Guides for major and trace elements), two serpentinised lherzolites (WPR-1a, UB-N), a komatiite (OKUM; certified reference material according to ISO Guides), a pyroxenite (NIM-P) and a norite (NIM-N), which encompass various rock types with very low Sm and Nd mass fractions (from ng g^-1 to sub-ng g^-1 levels), were analysed. The measurement results of these reference materials (RMs), demonstrate that the measured ¹⁴⁷Sm/¹⁴⁴Nd and ¹⁴³Nd/¹⁴⁴Nd ratios are in good agreement with previously published values obtained by the TIMS and MC-ICP-MS techniques. Notably for OKUM, HARZ01, DZE-1, DZE-2 and NIM-D, this study provides the first reported data on ¹⁴³Nd/¹⁴⁴Nd ratios. This protocol has great potential for Sm–Nd analysis of ultra-low Nd abundance samples in geochemistry, cosmochemistry and environmental sciences (e.g., peridotite, garnet, meteorites, dust, etc.). Therefore, the high sample throughput inherent to MC-ICP-MS can be fully exploited in these research fields.

Mica crystals have a highly asymmetric structure, arranged in sheets of two tetrahedral layers bonded to a single octahedral layer. The individual sheets are only weakly bonded, leading to perfect basal cleavage. The recent proliferation of in situ laser ablation-based Rb-Sr geochronology of mica makes it critical to understand if orientation of the crystal lattice relative to the laser beam may impart a differential ‘matrix’ effect on Rb-Sr ratios during ablation. Analyses of mica crystals from eight different samples, including biotite, muscovite and phlogopite, mounted with their c-axes approximately parallel (flat-mounted) and perpendicular (vertically mounted) to the incident laser beam, result in dates that are statistically indistinguishable. Moreover, and consistent with previous work, analysis of vertically mounted crystals generally resulted in less within-spot variation in ⁸⁷Rb/⁸⁶Sr, and is, therefore, the recommended orientation for Rb-Sr geochronology measurements, where practical.

NIST SRM 610 and 612 (Trace Elements in Glass) are routinely used for microanalytical measurements but were designed to be bulk-scale reference materials. This study investigates an approach to quantify the differences between values for elements obtained using the bulk techniques ICP-OES, INAA and CNPGAA, and values obtained using the predominant microanalytical technique LA-ICP-MS. The results from bulk techniques and LA-ICP-MS were also compared with currently accepted mass fractions reported in the Certificates of Analysis (CoA) and the literature. The element suite measured was based on the needs of the forensic and geological microanalysis communities, and included B, Ce, Hf, K, La, Li, Ti and Zr. These additional elements are either not included or do not have uncertainty values in the CoAs for NIST SRMs 610 and 612 but are available as community consensus values, which include uncertainties. The measurement results were processed using Monte Carlo (MC) uncertainty analysis for each technique to provide a comprehensive calculation of expanded uncertainties for use in future research. Measurements of mass fractions of the same element both within and between fragments in the LA-ICP-MS data were observed to be correlated due to the use of only one calibration material, which was Float Glass Standard (FGS) 2, as that reference material is not directly traceable to NIST SRMs 610 and 612, and is predominantly used in the forensic community. The MC treatment was expected to cause increases in the overall uncertainty values compared with traditional Guide to the Expression of Uncertainty in Measurement (GUM) treatment for all measurements, which was the case for LA-ICP-MS measurements of all elements in NIST SRM 610 and NIST SRM 612 (except for Mn in NIST SRM 610). However, for bulk measurements of Ce, Li and Rb in NIST SRM 610, and bulk measurements of Li, Mn, Ti and Zr for NIST SRM 612, the uncertainty decreased due to MC more precisely determining the uncertainty contribution compared with a more conservative approximation from GUM. All results were compared by using E_n scores to assess the relative agreement between bulk- and micro-scale measurements, CoA values and to community consensus values. The findings point out the limitations of the current forensic glass reference materials for high precision microanalytical measurements, especially due to the relatively high uncertainty values associated with Float Glass Standard (FGS) 2. This situation underscores the need for new reference materials specifically designed for homogeneity at the micro-scale for trace element measurement.

Trace element partitioning in carbonate minerals has shown potential in palaeoenvironment reconstruction, while one of its preconditions of application – the respective extraction of trace element mass fractions in diverse mineral phases in carbonate rocks – leaves room for methodological improvement. We tested a ten-step sequential leaching method to selectively dissolve and extract calcite and dolomite based on their different reactivities to dilute acetic acid, with a focus on strontium and barium release. A group of mineral samples and a group of rock samples were selected for the experiment. The constant release of Sr from both calcite and dolomite mineral samples indicates its uniform distribution in the two carbonate minerals, which is consistent with prior conclusions that Sr is incorporated in the carbonate lattice, substituting for Ca. For carbonate rocks, the Sr and Ba contents present linear correlations with the ratio of calcite and dolomite, as well as Ca/(Mg+Ca) ratio dissolved in each leaching step, suggesting that the determination of their mass fractions in the two minerals can be achieved by regression. Although the Ba abundance in mineral samples is similar to that of Sr, its pattern of release from rock sample powder shows significant non-carbonate contributions. Based on the results of the sequential leaching, we design a multi-step procedure for the separate extraction of Sr and Ba in calcite and dolomite, and a case study is conducted to demonstrate its applicability, the results of which show a significantly lower Ba content in the carbonate minerals compared with bulk Ba concentrations, emphasising the importance of being cautious when using element abundances in carbonate rocks to reconstruct geochemical properties of the palaeoenvironment.

The abundances of rhenium (Re) and platinum-group elements (PGE) and their variation patterns provide crucial insights into the evolution of planetary bodies, including the Moon. The objective of this study is to evaluate the applicability of the Carius tube and HPA-S digestion methods, as well as online and offline separation and detection techniques, for determining the mass fractions of Re and PGE in meteorites. The findings demonstrated that HPA-S is capable of completely dissolving refractory minerals and is a more effective dissolution method for meteorite samples than the Carius tube approach. The combination with cation exchange resin and online matrix separation allows for complete control over interfering elements, making it particularly promising for analysing extraterrestrial samples with high Zr/Pd ratios, such as Martian meteorites and lunar rocks. However, it was observed that PEEK tubing adsorbs Pd and Pt ions, resulting in significantly reduced recoveries of these elements during chromatographic separation. Therefore, the use of PEEK during chromatographic separation is not recommended. The optimised measurement procedure was validated using PGE reference materials OKUM, GPt-3 and UMT-1, and the resulting measurement values were found to agree with the literature values.

This study reports on the development of three spodumene reference materials referred to as Curtin University (CU) Tri-1, Kun-A-1 and MG-1 for calibrating the instrumental mass fractionation for oxygen isotope measurement by secondary ionisation mass spectrometry (SIMS). Millimetre-sized fragments were prepared from gem-quality spodumene crystals with chemical compositions close to the ideal spodumene end member (LiAlSi₂O₆). From these fragments, six subsamples were extracted for laser fluorination isotope ratio mass spectrometry (LF-IRMS) to determine the bulk oxygen isotope ratio of the three materials and confirm their homogeneity on the mg scale. The bulk δ¹⁸O (VSMOW) values are 11.29 ± 0.04‰, 9.12 ± 0.10‰ and 15.13 ± 0.08‰ (all 2SE, standard error of the mean) for materials Tri-1, Kun-A-1 and MG-1, respectively. A random selection of twenty or more fragments from each material was subjected to SIMS analysis. Repeatability of SIMS δ¹⁸O measurements was at most 0.24‰ (2s), indicating oxygen isotopic homogeneity on the ng scale. Crystal orientation effects potentially affecting SIMS analysis were systematically evaluated and found to be absent at levels equivalent to the repeatability of the method. Applications of the new materials lie mainly in furthering research on pegmatite formation and tracing of raw materials by providing the means for accurate, in situ oxygen isotope measurement in spodumene.