• Editor in Chief:
    Prof. Xian-Hua Li
  • Executive Editor:
    Prof. Wei Guo
  • Associate Editors:
    Prof. Michael Dürr
    Prof. Wei Hang
    Prof. Zhaochu Hu

    Print ISSN:0195-5373
    Online ISSN: 2708-521X
    2023 SCI IF: 3.4 (JCR, Q1)

          The ATOMIC SPECTROSCOPY is a peer-reviewed international journal started in 1962 by Dr. Walter Slavin. In November 2019, its ownership was transferred to Atomic Spectroscopy Press Limited (ASPL), Hongkong, P.R. China. It is intended for the rapid publication of Articles, Review/Mini-review, or Letters/Communications in the fields of elements, elemental speciation, and elemental isotopic analysis by XRF, AAS, AFS, ICP-OES, ICP-MS, GD-MS/OES, TIMS, SIMS, AMS, LIBS, AMS, NAA, INAA, various microanalysis techniques, and related sample preparation techniques. Manuscripts dealing with (i) instrumentation & fundamentals, (ii) methodology development & applications, and (iii) standard reference materials (SRMs) development can be submitted for publication.

    Publishing frequency: Six issues per year 

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      Abstract:
      The direct determination of sulfur isotope ratios 34S/32S (δ34S), in atmospheric precipitation by triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS) is challenging owing to intense interference from polyatomic species of mass that affects all sulfur isotopes. Additionally, high background levels of sulfur often pose a challenge for accurately determining δ34S ratios at low concentrations in atmospheric precipitation samples. To address these challenges, a reliable method based on mass shift ICP-MS/MS was developed in this study. The δ34S ratio was determined at m/z 48 and 50 instead of at m/z 32 and 34 by using O2 as a reactive gas to shift the 32,34S+ ions to 32,34S16O+, thus avoiding on-mass interferences at m/z 32 and 34. The sulfur concentration in the background blank, which mainly originated from the Ar and O2 gas used during analysis, was reduced from 22.1 μg L–1 to 0.82 μg L–1 by purifying Ar and O2 using a gas trap. The δ34S measurements were not significantly affected by the sulfur concentration of the sample between 200 and 1000 μg L–1, and the atmospheric precipitation matrix did not affect δ34S determination using ICP-MS/MS. Therefore, the proposed method does not require strict matrix and concentration matching, simplifying the analytical process. The results obtained from atmospheric precipitation using the proposed method are consistent with those obtained by isotope ratio mass spectrometry, thereby validating the proposed method.
      Abstract:
      Lunar regoliths typically exhibit complicated mineralogy, texture, composition, and fine grain size, making them difficult to characterize using traditional mineralogical analytical methods. SEM-based automated mineralogy allows for quantitative and non-completely destructive assessment of bulk composition, mineralogical characteristics, and igneous rock types of lunar soils. Here, we use the TESCAN Integrated Mineral Analyzer (TIMA) to characterize a total of 79604 particles of Chang’e-5 returned lunar soil with a wide particle size range (>240 μm to <2 μm). The results showed that lunar soil mainly consists of pyroxene (36 wt. %), plagioclase (22 wt.%), glass (19 wt.%), olivine (9 wt.%), ilmenite (5 wt.%), SiO2 polymorphs (0.5 wt.%), apatite (0.2 wt.%) and troilite (0.2 wt.%), agreeing with those of the previous XRD and Raman analyses. The analytically calculated bulk compositions of the SiO2 (40.8 wt. %), MgO (6.8 wt.%), Al2O3 (10.8 wt.%), CaO (12.1 wt.%), and FeO (22.7 wt.%) were also consistent with those of the previous result obtained by wet chemical methods. The mineral association showed that basaltic pyroxene-plagioclase-olivine-ilmenite assemblages were the most common lithic clasts within lunar soil. These results indicate that Chang’e-5 lunar soil predominantly consists of local mare basalt. This study demonstrates the role of automated mineralogy technology in providing rapid, quantitative, and reliable mineralogical and compositional data, which are fundamental for investigating the bulk mineralogical and chemical characteristics of rare returned extraterrestrial materials.
      Abstract:
      Atom probe tomography (APT) is a cutting-edge technology capable of imaging three-dimensional atom distribution and measuring chemical composition at the sub-nano scale. Since APT samples are tip-shaped and have specific size requirements, several manufacturing methods based on focused ion beam (FIB) have been developed. In order to precisely preserve the region of interests (ROI) into the tip and also satisfy the need of correlative characterization between crystallographic information and chemical information, we developed a new approach of directly fabricating APT tips from the twin-jet electropolished transmission electron microscopy (TEM) thin disc. This method has been successfully demonstrated on a Ni-B disc sample. After its nanocrystalline structure been observed by TEM, APT tips were prepared and analyzed from the selected region of the very-edge of the center hole. The distributions of major elements from the sample itself and induced by FIB processing were also discussed. This approach exhibits universal applications, which can not only feature in the correlation between TEM and APT analysis, but also benefit for the Ga-sensitive materials as only minimum FIB processing is required.
      Abstract:
      Polygonati Rhizoma (PR), for which rapid geographical origin identification is crucial to ensure its efficacy and product authenticity, is a traditional Chinese medicine with multiple pharmacological effects such as hypoglycemic and anti-tumor effects. This study presents a rapid identification method of sliced PR geographical origin based on auto-focus laser-induced breakdown spectroscopy (LIBS) combined with interpretable machine learning. The spectral data of sliced PR samples from 8 producing areas were obtained by using the self-built auto-focus LIBS system without further sample processing. Various data preprocessing methods, feature variable selection methods, and classification algorithms were evaluated. The results showed that the combination of wavelet transform (WT), Model-Free (MF) algorithm, and area normalization (AN) outperformed each method used individually. Among the feature selection methods, iteratively retaining informative variables (IRIV), variable iterative space shrinkage approach (VISSA), and the successive projection algorithm (SPA), the fewest feature variables were selected by SPA. However, by combining with Linear discriminant analysis (LDA), K-nearest neighbors (KNN), Multilayer perceptron (MLP), and Support vector machine (SVM), a good prediction accuracy of 95.00% was still achieved by SPA-SVM. Furthermore, according to the importance analysis by the SHapley Additive exPlanations (SHAP) algorithm, Ca was the most essential element to distinguish sliced PR samples from different geographical origins, followed by other elements in the order of Fe, Ti, Sr, C, Mn, Mg, Li, Ba, K, H, Si, and Na. This study provides a simple, rapid, and reliable analytical approach for PR authentication, which has broader applications in medicinal material and food product verification.
      Abstract:
      Lunar glass beads, including volcanic and impact origins, have become key targets for in-situ U-Pb dating using secondary ion mass spectroscopy (SIMS) to trace the thermal evolution and impact history of the Moon. However, the accuracy of SIMS U–Pb dating results is questionable without careful evaluation of matrix effect because of the largely variable major element contents of lunar glass beads which are also significantly different from the commonly used glass standards. In this study, we used seven glass stanards with large variation of compositions, including three MPI-DING glasses, two USGS glasses, ARM-3 glass, and LMG-4 glass with composition simulating the Chang’e-5 lunar soils, to investigate the U-Pb fractionation behavior in SIMS analyses. Our results revealed more than a threefold variation in Pb+ ion yield, which positively correlated with the total FeO content (FeO(t)), and an eightfold variation in U+ ion yield, which negatively correlated with FeO(t). The relative sensitive factor (RSF) of (206Pb+/238U+)/(206Pb/238U) shows a variation of over 28-fold. Therefore, the traditional U/Pb calibration method based on only a single standard is insufficient to correct such a significant matrix effect. We propose a calibration protocol based on a linear relationship between ln((206Pb+/238U+)/(206Pb/238U)) and ln(UO2+/U+), or alternatively, ln(206Pb+/238U+/206Pb/238U) vs. ln(UO+/U+), and ln(206Pb+/UO+/206Pb/238U) vs. ln(UO2+/UO+). This method requires at least two glass standards with a large range of FeO(t) to effectively correct for matrix effects. Additionally, we recommend revised 206Pb/238U values for those glass standards that lack values determined by ID-TIMS, based on the observed fractionation rule in this study.
      Abstract:
      Lunar glass beads, formed through impact and volcanic processes, are used in SIMS U-Pb dating to provide valuable insights into the Moon’s volcanic activity and impact history. However, lunar glass beads exhibit a wide range of chemical compositions deviating from the commonly used glass reference materials. The lack of glass reference materials with high FeO content presents a challenge for correcting matrix effects in SIMS analyses of impact glasses with variable FeO contents. This study prepared and preliminarily characterized a new synthetic glass reference material (LMG-4) with compositions analogous to those of Chang’e-5 soils and mare basalts, plotting in the center of the published compositional range of Chang’e-5 impact glass beads. This glass exhibits significantly higher FeO and lower SiO2 contents than other available reference glasses, fulfilling the requirements for high-FeO glass reference materials. U-Pb-Si-O isotope ratios and Fe2+/ΣFe ratio were determined using bulk ID-TIMS, MC-ICP-MS, IRMS, and potassium dichromate volumetric method. The homogeneity of LMG-4 is confirmed through EPMA and SIMS spot analyses. This new synthetic glass reference material offers a potential solution for correcting matrix effects in U-Pb-Si-O isotope analyses of high-FeO glass using in situ microanalytical techniques.
      Abstract:
      Zircon U-Pb geochronology has been widely used for determining the age of geologic processes. However, for very ancient zircon samples (e.g., ~3.8 Ga), the quality of U-Pb dating results may be affected by the relatively high-grade of Pb loss caused by the crystal damage through radioactive decay of U and Th. Here, we present a comparative study to explore the effect of thermal annealing (TA) and chemical abrasion (CA) on zircon U-Pb geochronology using zircon samples from some of the oldest igneous rocks on Earth (the Acasta Gneiss and the Muzidian Gneiss complexes), with the goal of getting better constrained zircon U-Pb ages of ancient rocks. Prior to the laser ablation dating experiments, all zircon samples and reference standards were thermally annealed (850 ℃ ~ 1050 ℃/48 h), and a subset of thermally annealed zircon samples was then selected for chemical abrasion treatment (partial dissolution using hydrofluoric acid at 170 ℃ for12 h), in order to remove radiation damaged domains. The results show that the U-Pb ages of CA zircon grains appear to be more concordant with smaller MSWDs than those of the TA and untreated zircon grains, indicating that the partial dissolution treatment of thermally annealed zircon grains effectively removed domains with Pb loss, leaving the rest of the zircon crystal lattice relatively unaffected. Therefore, for complex and ancient (> 3.8 Ga) zircon samples, chemical abrasion prior to laser ablation is shown to be useful for reducing Pb loss and data scatter. Thermal annealing appears to improve the matrix match between the unknown and reference zircon grains, which is especially useful for the dating of high U, young zircon samples. Additionally, our results show no systematic difference in the trace elements and Hf isotopic compositions between treated and untreated zircon samples, which demonstrates that the treatments do not have negative effect on the trace elements and Lu-Hf isotopic compositions in zircons.
      Abstract:
      Accurate determination of platinum group elements (PGEs) in active pharmaceutical ingredients (APIs) is critical due to stringent regulatory requirements and the potential toxicological effects of these elements. In this study, a microwave-assisted wet digestion (MAWD) method was developed to allow interference-free determination of PGEs, including Os, in APIs by inductively coupled plasma mass spectrometry (ICP-MS). Five widely used API samples were selected and a study of interferences was performed. The evaluated conditions included the composition of the digestion solution, and sample mass. The calibration and washing solution mediums were also evaluated: 5% HCl solution or a stabilizing solution (composed of acetic acid, thiourea and ascorbic acid). Furthermore, carbon interference (up to 2000 mg L-1 of C), which is critical for PGE determination by ICP-MS, was evaluated, and it was observed that C concentrations higher than 800 mg L-1 caused interferences for PGE determination, with the exception of Os). The method was validated according to the United States Pharmacopeia (USP). The optimized conditions for the proposed MAWD method were 500 mg of sample and a mixture of HNO3+HCl (1+1, 6 mL) as digestion solution. The 5% HCl solution was suitable for the determination of all PGEs, except for Os. In the case of Os, the stabilizing solution, added to samples, blanks, standards, and as washing solution, was necessary for its quantitative determination. The proposed procedure allowed quantitative PGE recoveries, including Os, using an efficient and relatively simple sample preparation method based on MAWD. Furthermore, limits of quantification were suitable for PGE determination according to USP requirements.
      Abstract:
      Gallium is a technology-critical element whose concentration increases owing to industrial activity. To study anthropogenic contamination in maritime Antarctica (Nelson Island, South Shetland Islands), it was necessary to develop an analytical method to determine the trace Ga content in Antarctic flora. The determination of Ga using electrothermal atomic absorption spectrometry (ETAAS) is a seemingly routine analytical task; however, the commonly used atomic lines of 287.4?nm and 294.4?nm appear to be unsuitable for analytical use. In this study, the fundamental aspects of Ga determination were investigated, and an atomic line at a wavelength of 417.2?nm was recommended for the analysis of environmental samples. The Ga content in mosses, lichens, mushrooms, and grass samples from Antarctica are published here for the first time. Based on the Ga content of lichens as biomonitors of atmospheric pollution, it can be assumed that contamination of the studied locality through atmospheric deposition is low.
      Abstract:
      Certified Reference Materials (CRMs) are a widely recognized tool for the comparability of measurements taken in different times and spaces through their “traceability chain”. However, aqueous CRMs used as calibrants which allow tracing to the SI units are urgently needed especially for the speciation analysis CRMs due to the difficulty of development and certification for them. Herein, we presented two new aqueous trimethyllead reference materials. In the certification campaign, two important steps were included: 1) a traceability chain to the standard reference material GBW08619 which is a primary Pb(II) calibrant solution was set up; 2) isotopic variations of lead in trimethyllead (TML) and GBW08619, were introduced to the certified values and combined uncertainties. This paper describes in detail the homogeneity and stability studies, impurity assessment with nuclear magnetic resonance spectroscopy (NMR) and high-performance liquid chromatography - inductively coupled plasma mass spectrometry (HPLC-ICP-MS), traceability assurance protocol and the inter-laboratory co-certification campaign for the certification of their TML contents. Consequently, two CRMs (GBW(E)080971: (92.73±3.15) μg g-1 as Pb, k=2 and GBW(E)080972: (0.740±0.030) μg g-1 as Pb, k=2) are now available.
      Abstract:
      In forensic science, trace evidence establishes links between victims, suspects, and crime scenes. Head hair commonly serves as a reliable biomarker because it contains a permanent record of elements from an individual's body. By substituting CF4 reaction gas for polytetrafluoroethylene powder, this work modifies and re-optimizes a previous method for determining the sex of humans by directly analyzing hair samples via electrothermal vaporization with detection by inductively coupled plasma optical emission spectrometry. Hair samples were washed in portions of doubly deionized water, dried, and ground into a fine powder before analysis. Data processing included the use of an Ar emission line to compensate for sample loading effects on the plasma via point-by-point internal standardization. The peak areas were then integrated before multivariate analysis by principal component analysis (PCA) and linear discriminant analysis (LDA). Using the same predictor elements as the original method (Mg, S, Sr, and Zn), LDA and PCA remained effective at accurately predicting the sex of female and male samples despite using a different chemical modifier and instrumental operating conditions, indicating method robustness. This work thus offers an alternative method that uses a more affordable and accessible carrier agent at no cost to the original method's reliability.
      2024,45(4),246-258
      DOI: 10.46770/AS.2024.167
      Abstract:
      Particle size distribution (PSD) is a key feature of mineral fractions in soils and sediments. It directly affects many physical and mechanical properties that are closely related to the geological origin and evolution of soils and sediments. However, precise PSD measurement is still unrealized, especially for fine and precious samples such as lunar soils which require a noninvasive and nondestructive methodology. In this study, using Laser Diffraction Particle Size (LDPS) analysis as a reference, we compared PSD results of lunar soil simulants measured using three-dimensional X-ray Microscopy (XRM), Optical Microscopy (OM), and Scanning Electron Microscopy (SEM) approaches. Our experimental results showed that the PSD (in numbers) measured by the different methods was not consistent, whereas the PSD (in volume/area) showed some consistency, at least within a certain size range. Comparatively, (i) SEM reliably measured particles in the range of ~0.1-10 μm, (ii) OM was effective for particles with sizes ranging from ~10 to 75 μm, and (iii) XRM effectively measured those particles with sizes ranging from a few microns to a few hundred microns and showed relatively positive consistency with the LDPS result especially for particles above ~75 μm. By employing the Boltzmann model to integrate the particle size accumulation (PSA) data from different measurement methods, we propose a multi-approach method for the precise determination of particle size. This method can be applied for the particle size analysis of soils or regoliths returned from the Moon or other extraterrestrial objects.
      2024,45(4),259-265
      DOI: 10.46770/AS.2024.174
      Abstract:
      Spectroscopic interferences have long negatively impacted the accuracy of inductively coupled plasma mass spectrometry (ICPMS) analyses. Of these, oxide-based interferences, the combination of an analyte with oxygen producing a new ion 16 mass units greater than the original analyte, often proves most prevalent and difficult. A cheap and reliable method that permits the mitigation of oxide-based interference would be highly beneficial. Here-in, low sample uptake rate was used to reduce the formation of lanthanide oxide-based interferences in ICPMS analyses through temperature and Le Chatelier effects. Introduction of oxide forming solutions (50 μg L-1) composed of lanthanide elements at 1 mL/min yielded an average oxide ratio of 4.5 ± 7.2% while introduction at 50 μL L min-1 yielded 0.54 ± 0.26%. A similar method using 2% nitrogen gas in the bulk plasma concurrently decreased oxide-based interferences. The benefits observed with low sample uptake rate and a mixed-gas plasma were combined to virtually eliminate oxide based-interferences for many of the lanthanide elements and provide a modest signal enhancement compared to an Ar plasma operated at a higher sample uptake rate. For example, when comparing the best oxide reduction method to the worst, oxide formation is mitigated by 97%. Of the three sample uptake rates tested, 235 μL min-1 under mixed-gas plasma conditions offers the best balance between the oxide interferences mitigation and signal intensity. Ultimately, low sample uptake rate may prove essential in increasing ICPMS analysis accuracy while safeguarding resources and minimizing chemical waste for generations to come.
      2024,45(4),266-275
      DOI: 10.46770/AS.2024.079
      Abstract:
      In situ elemental analysis of carbonate matrices at the microscale is a rapidly developing and promising area of research with significant implications for fields including geology, environmental science, and biology. However, applications in these fields have been hampered by the lack of appropriate analytical reference materials and the ongoing need for improvements in analytical methods. This study used pure ooid sands from the modern Schooner Cays in the Bahamas as raw material due to their nearly consistent mineralogical compositions and uniform elemental distributions. A wet milling process was employed, and the Tyndall effect was used to isolate ultra-fine colloidal particles (most <1 μm). These particles underwent high-pressure compression, and the resulting pellets, namely OOID, were subsequently embedded in epoxy resin to ensure their long-term preservation and utility. Over a four-year study period, we confirmed that at least 28 elements remained homogeneously distributed within the reference material OOID. These results were achieved through rigorous relative standard deviation and Horwitz tests. The findings of this study underscored the crucial role of natural reference materials in ensuring quality control of in situ carbonate elemental analyses. Simultaneously, the study provided valuable new guidelines for preparing carbonate reference materials and improved the accuracy of in situ microanalytical methods for carbonate samples.
      2024,45(4),276-289
      DOI: 10.46770/AS.2024.103
      Abstract:
      This study presents a method for the reliable determination of 87Sr/86Sr in food grains, which are characterized by low Sr concentrations but high concentration ratios of Rb/Sr and K/Sr using multi‐collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The Sr/matrix separation procedure using Sr resin was optimized for a standard reference material of wheat flour (NIST SRM 1567b). Consequently, a high Sr recovery (97.0 % ± 1.2 %, mean ± 1 SD, n = 7) and effective Sr/matrix separation (e.g., 85Rb/88Sr intensity ratio at MC-ICP-MS measurements × 100 of 0.00014 % ± 0.00003 %, mean ± 1 SD, n = 7) were achieved. Furthermore, potential spectroscopic interferences caused by matrix ions were estimated by analyzing NIST SRM 987 solutions spiked with varying amounts of Rb or Ca using MC-ICP-MS. The proposed method was validated by analyzing eight standard reference materials of vegetal, animal, and geological origins studied previously, yielding 87Sr/86Sr ratios consistent with literature values, which demonstrates the applicability of the method across diverse sample matrices. Finally, the proposed method was applied to standard reference materials for which 87Sr/86Sr ratios are not reported to our knowledge (NIST SRM 1567a and b wheat flour). The 87Sr/86Sr ratios of NIST SRM 1567a and b were estimated to be 0.70895 ± 0.00005 (2 SD, n = 34), and 0.70898 ± 0.00003 (2 SD, n = 25), respectively.
      2024,45(4),290-297
      DOI: 10.46770/AS.2024.152
      Abstract:
      The pivotal role of vegetation uptake in the global biogeochemical cycle of mercury (Hg) necessitates investigation on Hg species and transformation within plants, which have been limited by methodological constraints. This study established a temperature-programmed thermal desorption method to provide well-resolved thermal release profiles of Hg complexes with various biomolecules and Hg in plant tissues, showing significant differences from those of inorganic Hg compounds. Wild plant tissues and Hg(0)-exposed poplar leaves in the laboratory demonstrated consistency with Hg complexes with biomolecules at 180℃, 220℃, and 280℃. Besides, thermal release profiles revealed that a proportion of plant Hg is more thermally stable compared to Hg-biomolecule complexes. Specifically, for wild plants, 13%-42% of Hg in leaves was released above 300℃, and 61%-76% of Hg in roots was released between 280℃ and 450℃, likely caused by different matrices, Hg sources, and transformation processes. Results also revealed a complete transformation of Hg(0) into oxidized Hg after foliar Hg(0) uptake. The notable Hg release from 180℃ to 450℃ raises concerns about Hg emissions during various biomass thermal processes, beyond biomass burning. Therefore, controlling Hg release in these processes is promising for reducing emissions and producing low-Hg biofuels.
      2024,45(4),298-308
      DOI: 10.46770/AS.2024.121
      Abstract:
      Advancements in Zn isotope analytical methods and their widespread application in geosciences underscore the importance of the purification process in isotopic measurements. Efficient purification of Zn, which involves separating Zn from matrix elements, is essential for accurately determining Zn isotopic compositions. This study proposes an optimized purification method that combines precipitation and a chromatographic procedure, significantly enhancing the purification efficiency. Using the established purification process, nine widely available geological-certified reference materials with known Zn isotopic compositions yield δ66Zn values that are in agreement with most previously published data within two standard deviations (2s) of repeat measurements. In addition, the effects of the presence of matrix elements have been evaluated using Neptune Plus MC-ICP-MS in a wet plasma mode. The average δ66Zn value of the multi-elemental Zn standard GSB-1, prepared by adopting GSB with different matrix elements, demonstrates good consistency with the long-term measured value of the pure GSB-Zn solution after precipitation and chromatographic separation. This enhanced purification protocol for Zn isotope measurement applies to a diverse range of geological samples and reduces the time and chemical reagents required for purification compared to conventional methods.
      2024,45(4),309-315
      DOI: 10.46770/AS.2024.173
      Abstract:
      Bacteremia is an extremely serious infectious disease with high mortality rate and increasing incidence. Early diagnosis and prompt treatment is key to improve the cure rate. In this study, we developed an automated sample pretreatment device based on microfluidic chip and online coupled it with ICP-MS for the simultaneous identification of E. Coli O157:H7 and Salmonella in human blood. This method realized automated sample loading, pathogen capture, elemental labeling, and signal desorption on the microfluidic chip through an automated liquid transfer system and E. Coli O157:H7 and Salmonella were detected simultaneously online by ICP-MS. The linear ranges of 400-80,000 CFU mL-1 for E. coli O157:H7 and Salmonella, as well as a method detection limits of 200 CFU mL-1 for E. Coli O157:H7 and 152 CFU mL-1 for Salmonella were obtained under optimum experimental conditions. The proposed approach realized the automated sample pretreatment and the simultaneous identification of two different kinds of bacteria in human whole blood, avoiding cumbersome sample pretreatment operations and sample contamination in conventional ICP-MS based procedures with elemental labeling strategy for bacteria analysis, demonstrating a strong potential for the clinical applications of bacteremia diagnosis.
      2024,45(4),316-323
      DOI: 10.46770/AS.2024.198
      Abstract:
      The increasing global popularity of traditional Chinese medicines (TCMs) raises significant concerns about potential contamination with organophosphorus pesticides (OPs). Portable analytical methods are particularly valuable for on-site pesticide analysis, enabling rapid screening and enhancing the safety assurance of TCM products. This study investigates the use of miniaturized microplasma atomic emission spectrometry (AES) as a promising tool for methyl parathion (MP) analysis in TCMs, leveraging the inhibition effect of OPs on butyrylcholinesterase (BChE) within a gold filament enrichment coupling point discharge chemical vapor generation atomic emission spectrometry (PD-CVG-AES) system. Specifically, BChE catalyzes the hydrolysis of acetylthiocholine chloride (ATCh) to form thiocholine (TCh), which contains sulfhydryl groups (-SH) that can strongly bind with Hg2+, leading to less efficient vapor generation and reduced AES signals of Hg2+. However, OPs like MP inhibit BChE activity and suppress TCh generation, resulting in the recovery AES signals. Ultra-trace levels of MP can be indirectly detected due to the high sensitivity of Hg2+ analysis using the gold filament enrichment PD-AES system. Under optimal conditions, the limit of detection (LOD) for the MP assay was 13 ng mL-1 within a range of 0.5 to 10 μg mL-1, with a relative standard deviation (RSD, n=5) of 0.8%. This analytical approach has proven effective in the detection of MP in TCMs, with advantages including ease of use and affordability.
      2024,45(4),324-335
      DOI: 10.46770/AS.2024.158
      Abstract:
      TC4 titanium alloy is a representative α + β dual-phase titanium alloy, which is widely used in engine blades and other components of aerospace equipment. This material typically requires heat treatment for strengthening to optimize its performance. To ensure that the heat-treated parts achieve ideal performance, it is necessary to test their physicochemical properties after heat treatment, such as microstructure, hardness, and elemental composition. To develop a rapid in-situ detection technology for the physicochemical states of heat-treated metal parts, a classification model was proposed by combining laser-induced breakdown spectroscopy (LIBS) with independent component analysis (ICA) and a deep neural network (DNN). The microstructure, Vickers hardness, and spectral characteristics of TC4 titanium alloy samples with different aging grades were analyzed. The spectral signals were preprocessed using the ICA method, and the results were used to establish a DNN model. The classification performance of the model was verified and evaluated using indicators such as the confusion matrix. The results show that the microstructure of TC4 samples can be regulated through solid solution and aging treatment, and the mechanical properties change accordingly. The uneven distribution of sample elements during microstructure control and the difference in ablated mass caused by different sample hardness contributes to the distinguishability of LIBS spectra of TC4 samples. The established ICA-DNN model facilitates dimensionality reduction and sensitive feature extraction of the physicochemical properties from the spectral data. Comprehensive evaluation results indicate that the classification performance of the model is strong, demonstrating the feasibility of using LIBS to characterize the physicochemical state of heat-treated metal materials. Compared to traditional detection methods, LIBS technology, as an emerging frontier detection technology, offers significant potential for in-situ, real-time, and micro-loss quality monitoring of heat-treated materials in industrial applications.
      2024,45(4),336-357
      DOI: 10.46770/AS.2024.041
      Abstract:
      Laser-induced breakdown spectroscopy (LIBS) has been successfully applied to various fields since its inception in the late twenty century. However, there are still challenges to overcome in order to enhance its performance in analytical experiments. These challenges include three major challenges: matrix effect, spectral interference, and self-absorption effect. This review specifically focuses on investigating the self-absorption effect, which disrupts the linear relationship between spectral line intensity and element concentration, thus affecting the the accuracy and sensitivity of LIBS analysis. The review explores different approaches to evaluate the extent of self-absorption, taking into account the evolutionary mechanism of this effect. Additionally, various methods for correcting spectra have been proposed, showing potential in significantly reducing self-absorption. Notably, the review emphasizes proactive measures to create non-self-absorbed conditions as the most effective approach to mitigate the self-absorption effect. Finally, the review presents a schematic description of exploiting self-absorption and highlights its promising prospects for future applications of LIBS.
      Abstract:
      On-line chemical vapor generation atomic fluorescence spectrometry (CVG-AFS) was, for the first time, used to determine trace copper in biological samples by merging acidified sample solution with potassium tetrahydroborate aqueous solution in the presence of micro-amounts of 1,10-phenanthroline. Nitric acid, for both sample digestion and chemical vapor generation, was used as the acid medium. CVG conditions and instrumental parameters were optimized for the best CVG efficiency, good gas/liquid separation, and efficient atomization/excitation. Under the optimized conditions, a limit of detection of 4 ng mL(-1) was obtained for copper, with a linear dynamic range of over three orders of magnitude. The proposed method was successfully applied to the determination of copper in biological certified reference materials.
      Abstract:
      A rapid, sensitive, and cost-effective method was developed for the determination of trace mercury in water samples by on-line coupling of flow injection (FI) sorption preconcentration with oxidative elution to cold vapor atomic fluorescence spectrometry (CV-AFS). race Hg(II) in aqueous solution was preconcentrated by on-line formation of mercury diethyldithiocarbamate complex (Hg-DDTC) and adsorption of the resulting neutral complex on the inner walls of a PTFE knotted reactor (KR). A mixture of 16% (v/v) HCl and 10% (v/v) H2O2 was used as the eluent to remove the adsorbed Hg-DDTC from the KR, then convert on-line the Hg-DDTC into Hg(II) prior to its reduction to elemental mercury by KBH4 for subsequent on-line CV-AFS detection. The tolerable concentrations of Cd(II) As(Ill) Se(IV) Fe(III), Co(II), Ni(II), and Cu(II) and Cu(II) for the determination of 0.1 mug L-I Hg(II) were 0.1, 10, 0.1, 0.1, 0.7, 1, 0.3, and 0.2 mg L-1, respectively. With a sample loading flow rate of 3.1 mL, min(-1) for a 60-s preconcentration, a detection limit (3sigma) of 4.4 ng L-I was achieved at a sample throughput of 36 samples h(-1). The precision (RSD, n = 11) was 1.7% at the 1 0, 1-mug L-1 Hg (11) level. The method was successfully applied to the determination of mercury in a certified reference material, GBW(E) 080392, and a number of local natural water samples.
      Abstract:
      A method based on?cloud?point?extraction?was developed to determine?cadmium?at?the?nanogram?per?liter?level?in?sea-water?by?graphite?furnace?atomic absorption spectrometry. Diethyldithiocarbamate (DDTC) was used as?the?chelating reagent to form Cd-DDTC complex; Triton X-114 was added as?the?surfactant.?The?parameters affecting sensitivity and?extraction?efficiency (i.e., pH?of?the?solution, concentration?of?DDTC and Triton X-114, equilibration temperature, and centrifugation time) were evaluated and optimized. Under?the?optimum conditions, a preconcentration factor?of?51.6 was obtained for a 20-ml, water sample.?The?detection limit was as low as 2.0 ng L-1 and?the?analytical curve was linear?in?the?10.0-200.0 ng L-1 range with satisfactory precision (RSD < 4.7%).?The?proposed method was successfully applied to?the?trace?determination?of?cadmium?in?seawater.
      Abstract:
      The analytical procedure for the determination of trace rare earth impurities in high purity neodymium oxide (Nd2O3) by ICP-MS is described. The effect of ICP-MS operating parameters on the REO(H)(+)/RE+ production ratio was studied in detail, and the optimal ICP operating conditions were established. In this context, the relationship between REO(H)(+)/RE+ production ratio and the bond strength of the rare earth oxides is also discussed briefly. For the correction of the spectral interference induced by the matrix (neodymium), a simple correction equation was used for correcting the interferences of the polyatomic ions NdO+ and NdOH+ with Tb-159 and Ho-165. The proposed method was applied to the determination of trace rare earth impurities in high purity Nd2O3\, and the analytical results were in good agreement with the recommended reference values.
      Abstract:
      A powerful multielement analytical technique using laser ablation Inductively coupled plasma source mass spectrometry (LA-ICP-MS) for the sensitive determination of trace impurities in thin glass filaments, used as reinforcing material in the construction industry, was developed. The trace analysis was carried out directly on very thin solid strands (without any sample preparation steps) by LA-ICP-MS whereby a bundle of thin glass fibers (with a filament diameter of about 10 - 20 mum) was fixed on a thin, special tape of a target holder. The fibers were ablated in the ablation chamber with the aid of a commercial laser ablation system using a Nd-YAG laser at a wavelength of 266 nm). In order to verify the trace analytical data, the ablated T-glass fibers were analyzed using a quadrupole (LA-ICP-QMS) and double-focusing sector field mass spectrometer (LA-ICP-SFMS). The detection limits of the trace elements in glass fibers using the LA-ICP-MS with a quadrupole analyzer were in the sub mug g(-1) range, whereas using a sector,field mass spectrometer (LA-ICP-SFMS) the detection limits could be Improved by 3-4 orders of magnitude down to the low and sub ng g(-1) range. The multielement trace analytical method, developed for high-purity glass fibers, was applied to the determination of chemical composition on thin alkati-resistant glass and basalt fibers with finishing additives used in fine concrete for the building industry. The analytical results were quantified using standard reference materials (SRMs) of glass matrix, such as the NIST 612 glass SRM and the basalt geological reference glasses, KL-2G and ML3B-G, for the trace analysis of basalt glass fibers. The experimentally determined relative sensitivity coefficients (RSC) in LA-ICP-MS for both SRMs varied between 0.2 and 3 for most of the elements. An increase of the relative sensitivity coefficients was observed with increasing mass. The relative standard deviation (RSD) of most elements (N = 3) was T between 2 and 10%. The results of the trace element concentrations by LA-ICP-MS using different instrumentation are in good agreement.
      Abstract:
      A?sequential?injection?system?for?on-line?ion exchange separation and?preconcentration?of trace level amounts of metal ions with ensuing detection by electrothermal atomic absorption spectrometry (ETAAS) is described. Based on the use of?a?renewable microcolumn incorporated within an integrated lab-on-valve microsystem, the?column?is initially loaded with?a?defined volume of beads of an SP Sephadex C-25 cation exchange resin. After having been exposed to?a?metered amount of sample solution, the loaded bead suspension is precisely manipulated within the valve to allow reproducible elution of the retained analyte by 30 muL nitric acid (1: 16,v/v) which, via air segmentation, are then transported into the graphite tube for quantification. The content of the used?column?is afterwards discarded and new?column?material is aspirated for the next run. The ETAAS determination is performed in parallel with the?preconcentration?process of the ensuing sample. The performance of the?system?is demonstrated for the determination of bismuth. With 2.4-mL sample loading, an enrichment factor of 33.4,?a?detection limit of 27 ng 1:1, along with?a?sampling frequency of 10 h(-1) was obtained. The relative standard deviation was 2.3% for the determination of 2.0 mg 1:1 Bi (n = 7). The procedure was validated by determination of bismuth in?a?certified reference material CRM 320 (river sediment) and by bismuth spike recoveries in two human urine samples.
      Abstract:
      A?sequential?injection?system?for?on-line?sorbent extraction?preconcentration?in electrothermal atomic absorption spectroscopy was developed for the determination of trace thallium in geochemical samples. The TlBr4-1 complex was adsorbed on?a?20-mu L micro-column?(located at the tip of the furnace sampling probe) packed with XAD-8 resin. After sequentially aspirating separate zones of acetone, rinsing acid, and sample (pretreated with bromine) into?a?2.5-m long, 1-mm i.d. holding coil, the flow was reversed and directed to the?column. Sample loading, analyte adsorption,?column?rinsing and analyte elution were achieved within?a?single reversed syringe stroke. The adsorbed analyte was eluted into the furnace with 50 mu L acetone. Mutual mixing between sample, rinsing acid, and eluent were prevented by separating the zones with small air segments during metering. Tightening of?column?packing was avoided by?a?slight back-suction through the?column?after each operational cycle. With 1-mL sample loading, an enrichment factor of 15 was obtained with?a?detection limit of 18 ng/L thallium (3 sigma).?A?precision of 2.4% RSD (n=11, 4 μ g/L) and?a?sampling frequency of 11/hour were achieved. The method was applied to the analysis of geochemical samples. The results were in good agreement with the certified values of standard reference geochemical materials.
      Abstract:
      The metal content in several TCM drugs was determined by ICP-MS. The efficiencies of different sample digestion methods were compared. Since one of the products studied is known to contain arsenic sulfides as a main ingredient, a solvent fractionation scheme was developed and applied to speciate As in the product. The metal content in the same TCM drug produced by different manufacturers was compared. The concentration of some metals such as Pb and Cd differs widely with different manufacturers, suggesting that their origin is primarily from external contamination. The high sensitivity and precision of the ICP-MS technique offers considerable advantages over conventional ICP-OES techniques for the analysis of complex samples such as TCM materials. Standardized analytic protocols based on ICP-MS are being developed fur the determination and characterization of metals and trace elements in TCM materials for product quality assessment.
      Abstract:
      Theory, design, and operation of a dynamic reaction cell for ICP-MS

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