Abstract:The information of metal constituents in complex samples is crucial for understanding the physicochemical properties and formation mechanisms of samples. Moreover, direct analysis of metal constituents in such samples without sample pretreatment not only enhances analytical efficiency but also facilitates the elucidation of physical and chemical relationships among the components, which has attracted wide spread attention. Mass spectrometry possesses remarkable advantages in both qualitative and quantitative analyses of metal constituents. This review systematically summarizes recent advances in mass spectrometry-based methods for the direct analysis of metal constituents over the past decade. Unlike existing reviews, this work offers a overview of both hard ionization and soft ionization mass spectrometry techniques applied to the direct analysis of metallic elements. In this review, we present the fundamental principles of mass spectrometry relevant to this application, highlight representative applications across diverse fields such as environmental science, geology, and materials science, and critically discuss the advantages and limitations of each approach. Finally, we outline future research directions for advancing mass spectrometry in the direct analysis of metal constituents. This review provides valuable insights for the development of high-performance analytical methods for metal constituent analysis.

Abstract:The main purpose of this article is to attract attention to the molecular emission of rare earth elements (REEs) in laser-induced plasma (LIP) as a potential opportunity in addition to traditional atomic and ionic LIBS. This is relevant for analyzing REE-bearing materials of various types during exploration, mining, and processing. The first potential application is preliminary radiometric sorting, which enables the removal of a substantial portion of the waste rock from the entire technological process, making the development of even relatively low-grade deposits profitable. Additionally, products may be derived from the old waste, resulting in a positive ecological impact. Promising directions include electronic waste sorting, quantification of REE in Nd–Pr–Fe-B and Sm-Co super magnets, remote detection in nuclear-related applications, and the analysis of a small amount of a specific REE in the presence of a higher level of another one.

Abstract:The Chang’e-6 (CE-6) mission returned the first farside lunar soil samples which are of great importance to understand the geological diversity and evolutionary history of the Moon. In this study, we employed a Raman-based automated particle analysis system to investigate the grain size and mineral composition of the CE-6 soil, which are compared with results of the nearside Chang’e-5 (CE-5) soil. Our analyses reveal that the CE-6 soil exhibit small grain size (mean = 4.4 μm) as the CE-5 soil, but markedly higher glass content (37.8 vs. 8.3 vol%), slightly higher plagioclase abundance (39.0 vs. 37.5 vol%), and lower pyroxene (18.4 vs. 39.4 vol%) and olivine (2.3 vs. 9.8 vol%) content. Raman spectroscopic analysis further reveals a marked magnesium enrichment in CE-6 olivines (most grains with Fo of 40-90) compared to their CE-5 counterparts (most Fo < 60). Notably, evident compositional zonation in olivine (Fo of 66 to 47) is observed for a CE-6 lithic clast, which likely represents ejected crustal material with complex magmatic interactions. These findings support that the CE-6 scooped soil contains substantial non-mare components that is limited in the CE-5 sample. Given very low olivine abundance in the CE-6 landing site basalt, the wide range of olivine Fo in CE-6 soil reflects the contribution of olivine-bearing, mafic crustal lithologies such as magnesian-suite and ferroan anorthosite or even of material from the lunar mantle. This study highlights the capability of non-destructive, rapid and simultaneous determination of particle size and mineral composition with Raman-based analytical techniques, which enables direct analyses of complex soil samples and provides new insights into the mineral compositions of landing site basalts and also non-mare ejecta of the near and far sides of the Moon.

Abstract:In-situ preconcentration of volatile Se and Cd species in the dielectric barrier discharge (DBD) atomizer for subsequent analyte detection by atomic absorption spectrometry (AAS) was investigated. Quantitative trapping of selenium hydride in the DBD atomizer, followed by incomplete volatilization of trapped analyte species, was previously described in the simplest apparatus arrangement. In this work, two advanced constructions of both the DBD atomizer and its high voltage power supply source were tested to improve the preconcentration efficiency by increasing the volatilization efficiency of trapped Se species. Unfortunately, no significant improvement was found. The overall preconcentration efficiency ranged between 60 and 70% regardless of the apparatus set-up. In contrast to Se, in-situ trapping of volatile Cd species in the DBD atomizer for AAS was optimized for the first time in this work. Quantitative Cd trapping was observed at 17.5 kV with 3.5 mL min-1 O2 admixed to 300 mL min-1 Ar, while complete analyte release was achieved at 25.2 kV with 75 mL min-1 Ar. The preconcentration efficiency was quantified to 98 ± 7%. The sample loop volume was optimized to 0.15 mL, as higher sample volumes unfortunately led to a significant decrease in preconcentration efficiency due to analyte loss during the prolonged trapping step.

Abstract:The present study optimized the planetary ball milling of synthetic pyrrhotite doped with trace metals in order to enhance homogeneity. It has been demonstrated that milling at 400 rpm with acetone is an effective method of reducing particle size, whilst also preventing oxidation and secondary phase formation, in contrast to the process of dry grinding. Annealed samples demonstrated excellent trace element uniformity (RSD ~2-3%) by LA-ICP-MS, comparable to or superior to existing standards. The work underlines the pivotal role of milling conditions in the production of reliable sulfide standards, which are essential for accurate analysis in geochemistry and materials science.

Abstract:A novel on-site analytical approach for the determination of trace metal ions and nanoparticles in environmental water is presented, utilizing a self-developed amphiphilic material that enables rapid enrichment and precipitation of analytes. This material, consisting of a hydrophobic polyhedral oligomeric silsesquioxane (POSS) core covalently linked to functional hydrophilic ligands, spontaneously self-assembles in aqueous solutions to form micron-scale aggregates, thereby facilitating efficient extraction and phase separation without heating, pH adjustment, or auxiliary agents. After enrichment, the precipitate was readily redispersed and subjected to rapid spectrophotometric analysis directly in the field. The method achieved outstanding enrichment factors (up to 495 for metal ions and 475 for nanoparticles), high extraction efficiencies (95–99%), and excellent selectivity for analytes such as Cu2?, Pb2?, Ag nanoparticles, and ZnO nanoparticles. Notably, the detection limits and analytical performance of the on-site spectrophotometric method after preconcentration were significantly improved and comparable to those of laboratory-based atomic absorption spectrometry (AAS). For example, the limit of detection for Cu2? was reduced to 0.63 μg/L (24-fold improvement), for Pb2? to 11.25 μg/L (10-fold improvement), for Ag nanoparticles to 0.056 μg/mL, and for ZnO nanoparticles to 0.065 μg/mL, all with substantial increases in sensitivity after enrichment. The method also demonstrated high precision and accuracy with recoveries ranging from 91% to 108% and relative standard deviations below 5% for real water samples. The results obtained using this approach were in excellent agreement with those obtained using AAS, confirming its reliability. This study established a simple, rapid, and environmentally friendly platform for on-site spectrometric analysis of both metal ions and nanoparticles, providing a practical alternative to conventional laboratory instrumentation for environmental monitoring and analytical chemistry.

Abstract:The iodine-to-calcium (I/Ca) ratio in marine carbonates can indicate changes in seawater redox. The use of inductively coupled plasma mass spectrometry (ICP–MS) to determine the I/Ca ratio in carbonates is challenging owing to low iodine content, volatility, and significant Ca matrix effects. In this study, an online extraction device was designed to evaluate the influence of extraction time on the detection of iodine signals. The intensity of I signal increased from 0 to 3 min after the addition of 2% HNO3, and a stable I signal was obtained from 3 to 8 min. After 8 min, the analytical signal decreased owing to the volatilization of iodine. Experimental results revealed a linear relationship between the intensity of I/Ca ratio and the concentration of I/Ca ratio, indicating that Ca can serve as an excellent internal standard (I/Ca ratio) to correct the attenuation of the I signal caused by Ca matrix effects. Therefore, a novel online acid extraction method coupled with ICP–MS was developed by strictly controlling extraction time (3–5 min) and using the I/Ca ratio for direct correction to obtain the final I/Ca ratio, with a detection limit of 0.02 μmol/mol and relative standard deviation ranging from 1.5% to 10.3%. The proposed method was applied to determine the I/Ca ratio in carbonate reference materials. The measured I/Ca ratios were consistent with the reference values.

Abstract:This proof-of-concept study investigates the application of femtosecond laser-induced breakdown spectroscopy (fs-LIBS) for a rapid, almost non-destructive assessment of surface hardness of 80CrV2 steel samples subjected to thermal treatment. Conventional hardness testing methods, such as Vickers and Rockwell, often necessitate extensive sample preparation, geometric requirements and can alter the material's surface, limiting their effectiveness for rapid assessments. In contrast, LIBS offers a contactless approach that minimizes surface damage while providing high spatial resolution. In previous work, we have already shown that nanosecond laser-induced breakdown spectroscopy (ns-LIBS) leads to melt and material redeposition around craters, consequently reducing the achievable effective spatial resolution. To circumvent these problems, we used femtosecond laser pulses to generate reproducible plasmas on 80CrV2 steel samples with varying degrees of hardness. By maintaining consistent parameters such as laser energy, surface roughness, and planarity, this method facilitates the analysis of spectral changes associated with mechanical properties. Our results identify a correlation between the intensity ratios of iron emission lines and material hardness, underscoring the method's sensitivity to microstructural material changes. As expected, the femtosecond laser-induced breakdown spectroscopy technique (fs-LIBS) produced significantly smaller ablation craters than ns-LIBS. When accounting for the fluence changes resulting from crater formation and making the necessary adjustments, repeated measurements at the same locations could become feasible in the future. A method using fs-LIBS could be a compelling alternative for hardness testing of finely structured or heat-sensitive components.

Abstract:Apatite has been widely applied as a reliable chronometer and geochemical tool for studies on genesis and provenance. Due to small quantity, most apatite standards for laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U?Pb dating were exhausted. Therefore, apatite reference materials with homogeneous age and abundant reserves are still necessary. The famous Qinghu (QH) monzonite in the western Nanling region, South of China was dated well at 159.5 ± 0.2 Ma (Isotope Dilution Thermal Ionization Mass Spectrometry (ID-TIMS) zircon U-Pb method) and 159.5 ± 0.7 Ma (Secondary Ion Mass Spectrometry (SIMS) zircon U?Pb method). The QH apatite grains selected from this monzonite are characterized by abundant reserves, euhedral crystals with sizes up to 1mm, high U and Pb contents of 137.30 and 7.82 μg/g, respectively, and a small Th/U value of 2.6. The QH apatite were analyzed as a quality control over five years in the SKLCMRE lab and yielded an accurate U?Pb age at 161.3 ± 0.8 Ma (N=110, MSWD= 1.1, calibrated by OD306), which agrees well with the published U?Pb ages within uncertainties. In combination of these age results and microscopic observations on cogenetic minerals in this rock, the zircon ID-TIMS U?Pb age of 159.5 Ma was accepted as a reference age for QH apatite. Up to now, it is the most suitable reference material for apatite samples from the Jurassic to Cretaceous periods owing to its high U and Pb content and formation age. An initial 207Pb/206Pb ratio of 0.837 ± 0.008, which was derived from LA-SF-ICP-MS analyses on intergrown feldspars, is consistent with the calculated value (0.836) in Stacey and Kramers (1975). One hundred and sixty analyses on QH apatite grains have a common lead percentage (f206) value ranging from 4.2% to 38.4% and form a good linear trend on the Tera–Wasserburg diagram. Using QH apatite as a primary standard in a two-stage calibration method, four known apatite standards, including OD306, 401, MAD1, and MM, have been accurately determined with age offsets of -0.7% to 1.2% by LA-ICP-MS. These age results are the same as those calibrated by apatite OD306 (-1.1% - 0.1%), MAD1 (-1.2% - -0.1%), and MM (-1.1% - 0.1%), and much improved than those calibrated by apatite 401 (0.3% - 1.4%) and Otter Lake (-3.4% - -2.2%). Moreover, in a method application, MRC-1 apatite yielded a lower intercept 206Pb/238U ages of 154.1 ± 5.3 Ma, which agrees well with the published ID-TIMS U?Pb age of 153.3 ± 0.2 Ma within uncertainty.

Abstract:Membrane filtration is an efficient technique for rapid and precise separation, yet challenges persist in distinguishing and selectively separating nanoparticles with identical elemental compositions, especially copper-based nanomaterials. Here, we report for the first time the immobilization of thiol-functionalized Fe3O4 nanoparticles (Fe3O4 RSH NPs) onto mixed cellulose ester membranes for the selective separation and preconcentration of copper nanoparticles (Cu NPs). The Fe3O4–RSH NPs–modified membrane demonstrated significantly greater retention of Cu NPs than CuS and CuO NPs of comparable size. The functionalized membrane exhibits exceptional separation performance, achieving over 90% retention of Cu NPs and an enrichment factor of ~23, as verified by inductively coupled plasma mass spectrometry (ICP-MS). Notably, the retention rate of Cu NPs remained unaffected by other copper species, demonstrating the excellent selectivity of the modified membrane toward Cu NPs. Under optimized conditions, the method reached a limit of detection (LOD) of 2.2 pg mL?1 for Cu NPs. Furthermore, the approach enabled successful detection of Cu NPs in river water samples from Chengdu. This strategy provides a rapid, reliable, and cost-effective pretreatment method for trace nanoparticle analysis in environmental samples and offers a promising platform for the development of low-cost, on-site nanoparticle monitoring technologies.

Abstract:The rhenium–osmium (Re–Os) isotopic dating technique has been extensively applied for the precise geochronological determination of black shale formations, effectively overcoming difficulties in dating chronologically challenging strata. Recent advancements have extended this methodology to limestone systems with substantially lower Re and Os concentration, thereby providing novel technical approaches for dating carbonate sequences. Clarifying the Re distribution in limestone is critical for optimizing experimental protocols and enhancing the accuracy and precision of dating results. However, carriers of Re and Os in carbonate rocks, particularly the radioactive parent element Re, remain poorly constrained. This study investigated Permian limestone samples from Guangde, Anhui Province, via integrated mineralogical characterization using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) and femtosecond laser ablation-inductively coupled plasma mass spectrometry (fs-LA-ICP-MS). The analytical results indicated that Re is predominantly hosted in authigenic phases such as organic matter (OM) and pyrite. Terrigenous quartz contains little to no Re, while calcite does not host Re. These findings emphasize that Re-Os pretreatment protocols should prioritize the complete dissolution of OM and pyrite, while avoiding the dissolution of silica phases.