Abstract:Buffer gas-assisted high-irradiance laser ionization time-of-flight mass spectrometry (BGA-LI-TOFMS) was used to determine the elemental distribution of Lycoptera fossils from the Dawangzhangzi Bed of the Yixian Formation in Liaoning Province, China. The Sr, Ba, and Pb images of the Lycoptera fossil highlight the fine structure of the skeleton, and the distribution of Fe and Si provides data regarding the preservation pattern and nature of pyritization in the Jehol Biota. The enrichment of toxic substances such As and H2S may be one of the reasons for the cluster mortality of Lycoptera. Meanwhile, the elemental analysis of the rocks in the fossil preservation shows that the paleoclimate indices MgO/CaO and Sr/Cu indicate dry and hot climatic conditions at that time. Meanwhile, the paleosalinity indicators (m value and Sr/Ba ratio) indicate a semi-saline to slightly saline water body. The paleoredox environment indicators (Th/U and V/(V+Ni) ratio) suggest an anaerobic environment with weak stratification and H2S in the bottom water. Thus, the elemental imaging and analysis of the Lycoptera fossil suggest that the organisms of Jehol Biota were preserved in the anoxic water environment and the toxic effect of hydrogen sulfide. Overall, BGA-LI-TOFMS is an adaptable technique for acquiring comprehensive geochemical information on fossils.

Abstract:MoS2 and ZnS quantum dots (QDs) were synthesized and applied as labels in magnetic immunoassays for the determination of myeloperoxidase (MPO) and osteopontin (OPN) via single-particle mode inductively coupled plasma mass spectrometry (ICP-MS). Primary MPO antibodies and primary OPN antibodies were captured by amino-modified magnetic nanoparticles, and the target biomarkers (MPO and OPN) were extracted and then specifically labeled with MoS2 QD-secondary MPO antibody and ZnS QD-secondary OPN antibody conjugates, respectively. MoS2 and ZnS QDs were employed as determination signal probes for ICP-MS measurements. Under the optimized conditions, the limits of detection obtained by magnetic immunoassay for MoS2 and ZnS QD-labeled MPO and OPN were 0.004 and 0.005 ng mL-1, respectively. The linear ranges for MPO and OPN were 0.01–50 and 0.02–50 ng mL-1, respectively. From six replicates, the relative standard deviations of MPO and OPN were found to be 3.5% and 3.2%, respectively. The proposed strategy was applied to determine the MPO and OPN levels in real human serum samples.

Abstract:Microplasma-induced vapor generation (μPIVG), particularly using only hydrogen, has attracted increasing attention in the field of atomic spectrometry. However, its application for field analysis of environmental samples remains limited owing to the difficulty of hydrogen storage and transportation. Herein, a non-noble metal electrode-based hydrogen evolution reaction (HER) was utilized as a safe and environment-friendly hydrogen supply method for the efficient μPIVG of Hg, Cd and Zn. Subsequently, HER-μPIVG was used for the sensitive field detection of Hg, Cd and Zn in environmental samples via miniature point discharge optical emission spectrometry (μPD-OES). In contrast to conventional hydrogen-enhanced μPIVG, hydrogen was produced in situ and in real time using a superior cathode composed of cobalt-phosphorous nanomaterial, eliminating the storage and transport of hydrogen requirements and improving the safety, sensitivity, and feasibility of μPIVG-μPD-OES. Under the optimized conditions, the limits of detection (LODs) were 0.8, 10, and 14 μg L?1 for Hg, Cd, and Zn, respectively, with relative standard deviations (RSDs) of < 4.7%. The accuracy and practicability of the proposed method were validated through Hg, Cd, and Zn determinations in two certified reference materials (CRMs) and several water samples with satisfactory results.

Abstract:In this study, a small platinized tungsten coil (TC) with a composite structure was utilized for the first time in a liquid sampling electrothermal vaporizer (ETV) setup. A novel direct sampling mercury (Hg) analyzer coupled with a dielectric barrier discharge (DBD) and a miniature fiber optic spectrometer (FOS) as an optical emission spectrometer was fabricated for the sensitive determination of Hg in environmental water. This ETV setup displayed a maximum sample volume of 100 μL and fulfilled the task of sequestering Hg during the dehydration and ashing processes under high temperature due to the formation of a platinum (Pt) and Hg amalgam. Under optimized conditions, the limit of detection (LOD) of Hg was 0.1 μg L-1 for a 100 μL liquid sample and the relative standard deviation (RSD) of 11 repeated measurements of Hg standard solution was 3.2%; the linearity (R2) was > 0.999 in the range of 0.4-100 μg L-1. The results for the GBW08063 sample (9.89 μg L-1) agreed with the certified values of certified reference materials (CRMs) (10 μg L-1), and the spiked recoveries were 94-100%, which proved favorable analytical accuracy and precision. The total analysis time was observed to be less than 3 min, and this small-sized ETV-DBD-OES system consumes only ~100 W of power while weighting less than 12 kg. Therefore, the proposed ETV-DBD-OES method demonstrates simplicity, suitable sensitivity, precision, and robustness, with promising application in the field for rapid water analysis for Hg.

Abstract:Magnetic covalent organic frameworks (COFs) were prepared using aminated Fe3O4 nanoparticles as the magnetic core and 1,3,5-tris(4-aminophenyl)benzene (TPB) and 2,5-dimethoxyterephthalaldehyde (DMTA) as monomers. The resultant Fe3O4@TPB-DMTP-COF was then post-modified with 3-ethynylthiophene through the “Aza D-A reaction”. The Fe3O4@COF-thiophene composite showed a high Brunauer-Emmett-Teller surface area of 898 m2?g-1, as well as a high content of S (5.27 w.t.%). Trace mercury (Hg), lead (Pb), and bismuth (Bi) ions were extracted from environmental water samples, followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. Extraction conditions, such as extraction pH, sample volume, adsorbent amount, extraction/desorption time and elution volume, were optimized. Under the optimal conditions, the three heavy metal ions were extracted from 150 mL of aqueous solution within 20 min and eluted with 0.1 mol L-1 HNO3 containing 8% cysteamine hydrochloride within 20 min. The method exhibited a high enrichment factor (188) and wide linear range of 3-5000 ng?L-1 for Hg2+/Pb2+ and 2-2000 for Bi3+, with the detection limits of 0.41, 0.97 and 0.47 ng?L-1, respectively. Furthermore, the reproducibility of the method was evaluated, and the relative standard deviations of Hg2+, Pb2+ and Bi3+ were found to be 7.5, 6.8 and 6.2% (n = 7, c = 3 ng?L-1), respectively. The accuracy of this method was verified by analyzing certified reference materials in environmental water, including GSB 07-1185-2000 (202047), GSB 07-1185-2000 (201239) and BY 400143 (B2003113). The application potential of this method was further evaluated by analyzing real environmental water samples. Target Hg2+ and Pb2+ ions concentrations were found to be 4.91 and 62.5 ng?L-1, respectively, in the East Lake water sample and 10.2 and 103 ng?L-1, respectively, in the Yangtze River water sample. The recoveries of target three metal ions were found to be 86.1-104 % in the two environmental water samples at three spiked concentration levels.

Abstract:Matrix-matched reference materials are important for in situ trace and isotope analyses. In this study, we developed an efficient method for preparing chemically homogeneous magnetite (MtTR-1) without adding a binder. The initial magnetite powder (d90 = ~80 μm) was milled to form micron (d90 = 3.0 μm) particles in an anhydrous ethanol suspension and argon environment using a high-energy vibration ball mill. The obtained particles were pressed into a magnetite cylinder (10 mm in diameter and 9.2 mm in height), sealed into a silver tube, and sintered at 500 °C and 1.2 GPa for 2 h. Laser Raman spectroscopy results indicated that high-temperature and high-pressure sintering did not induce any phase transformation. The smooth surface after polishing was subjected to repeated analyses via electron probe microanalyzer using a spot size of 5 μm and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) using spot sizes of 38-60 μm. The results indicated that the texture and chemical composition are homogeneous in MtTR-1. The smooth time-resolved signal intensities of elements, steep wall, and flat bottom of ablation craters also suggested homogeneity in the depth profile. Line profile analyses across the entire pressed pellet further demonstrated that the pellet is homogenous for the investigated elements. The concentrations of major and trace elements in MtTR-1 determined by ICP-OES and ICP-MS are used as the preferred values. The MtTR-1 can be cut into slices, repeatedly polished and used for in situ analyses. The proposed technique for producing magnetite can also be applicable to other minerals or rocks by optimizing the conditions, thus providing a new method for preparing reference materials for in-situ microanalysis.

Abstract:In this study, a laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) method is developed for in -situ quantitative imaging of trace impurity elements in Bi4Si3O12 (BSO) crystals. This method has unique advantages of low detection limit and high spatial resolution for the analysis of defects in crystal microregions. The regression coefficients of the calibration curves for each element were greater than 0.99, and the detection limits (DLs) were 17, 5, 7, 48, 5, 7, 16, 27, and 7 ng/g for 24Mg, 45Sc, 48Ti, 90Zr, 139La, 146Nd, 172Yb and 208Pb, respectively. The LA-ICP-MS measurements were in good agreement with the results obtained using conventional ICP-MS method. Segregation phenomena of elemental impurities in the axial direction of the BSO crystal can exist during crystal growth. Finally, the distribution of the impurity elements in the dendritic crystal defect region of the crystal was visualized. We believe that this work proposes a novel less-invasive analysis method for exploring the composition-defect relationship of crystals.