Atomic Spectroscopy

The Atomic Spectroscopy (ISSN: 0195-5373, JCR Q2) is a peer-reviewed journal dedicated to the rapid publication of innovative research on fundamentals, instrumentation, methodologies and applications across all areas of atomic spectroscopy and inorganic mass spectrometry. All published articles are freely available online and no article processing charges (APC) are required for publication.

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

Call for papers:

1. Special issue: 2027 Early Career Analyst

Aim: To amplify emerging voices, foster academic exchange, and support the professional development of early-career researchers. AS welcomes original articles across all atomic spectroscopy and inorganic mass spectrometry fields
Guest editors: Jorge Pisonero Castro, Willis B. Jones, Yanbei Zhu, Anika Retzmann, and John Thomas Caulfield
Submission deadline: 31 December, 2026
Please select: 2027 Early Career Analyst Special Issue upon submission.

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Evaluation-Dependent Performance Claims in Machine-Learning LIBS: A Reporting Framework

Toni Aaltonen*, Pekka Suominen

DOI: 10.46770/AS.2026.0078s

[Abstract] (0) [PDF 5.77 M] (3)

Abstract:
Machine-learning performance in laser-induced breakdown spectroscopy (LIBS) is often summarized by a single accuracy, F1 score, R2 value, or root-mean-square error (RMSE), although the same metric can support very different claims depending on how the evaluation data were constructed and accessed. This work proposes a LIBS-specific evaluation-claim reporting framework that records physical independence, instrument/session separation, and evaluation access/custody separately from a factor-specific Domain-Shift Matrix (DSM) describing composition and concentration, physical state/preparation, ambient environment, excitation/geometry, detection/spectral response, and signal quality. Three public-data case studies illustrate the framework. A retrospective EMSLIBS 2019 reanalysis with public-label access examines whether previously reported internal-to-benchmark discrepancies recur under a different fixed protocol; its sample-disjoint variants also alter training composition. In NASA SuperLIBS quantification (997,625 spectra; 2,511 materials), random-shot validation underestimated matched-energy error on unseen in-range and compositionally out-of-distribution (OOD) targets by 0.185 and 0.735 standardized RMSE, whereas target- and split-group-disjoint validation reduced the corresponding absolute discrepancies to approximately 0.028 and 0.060. In a separate controlled lithology-classification study, training rows, labels, weights, preprocessing, and candidate trajectories were held fixed while only the validation view changed; population- and energy-aligned group-disjoint validation reduced median absolute validation-to-test gaps in all eight evaluated situations, but better agreement did not consistently improve locked-test accuracy. These empirical analyses are illustrative case studies rather than inferential estimates of the causal effect of validation design. The framework makes explicit what a reported score estimates and the conditions under which that interpretation is supported.

Normalization of Laser-induced Breakdown Spectroscopy Using Laser-ablation-induced Ultrasonic Body Waves

Yuhua Hang, Jinliang Zhao, Shuhao Fan, Lu-Ning Li, Wei-Ming Xu, Rong Shu, Jinna Mei, Yan Qiu*

DOI: 10.46770/AS.2026.0015s

[Abstract] (2) [PDF 1.21 M] (26) [Supporting Information]

Abstract:
Shot-to-shot fluctuations in laser-induced plasma emission limit the precision of quantitative laser-induced breakdown spectroscopy (LIBS). This study evaluates an ultrasonic-assisted normalization approach in which laser-ablation-induced body waves, measured with a contact piezoelectric transducer, are used as an external indicator of shot-dependent ablation variability. For each analyte, the first-arrival acoustic feature was related to the within-specimen relative deviation of the corresponding emission line using a single model fitted from pooled calibration data; the fitted coefficients were then applied unchanged to the prediction specimens. For Mn, Cr, and Cu, normalization reduced the shot-to-shot relative standard deviation (RSD) from 6.87%, 4.27%, and 4.59% to 2.30%, 2.25%, and 2.87%, respectively. The corresponding average relative errors decreased from 1.41% to 1.13% for Mn, from 2.27% to 2.02% for Cr, and from 1.04% to 0.93% for Cu. For comparison with spectral internal standardization, Fe-dominant reference features were selected from the averaged spectra using spectral non-overlap, monotonic calibration behavior, calibration-set R2 and RMSEC, and calibration-sample RSD; prediction metrics were not used during feature selection. The selected reference features were 391.843, 427.966, and 458.218 nm for Mn, Cr, and Cu, respectively. Both the optimized Fe-ratio and ultrasonic-normalized models improved quantitative performance relative to the raw-intensity models, although the extent of improvement depended on the analyte and evaluation metric. Additional measurements showed that the body-wave response is sensitive to mechanical coupling and specimen thickness, while a synchronous comparison with an airborne-acoustic channel showed distinct temporal and statistical characteristics. Accordingly, the contact body-wave approach can serve as a configuration-dependent external reference when stable mechanical coupling can be maintained.

Doppler-shift Measurement of Pressure-dependent Expansion Velocities in Laser-ablated Molybdenum Plasma

Xiaohan Hu, Ding Wu*, Xinyue Wang, Haobo Heng, Ke Xu, Huace Wu, Ran Hai, Cong Li, Chunlei Feng, Hongbin Ding*

DOI: 10.46770/AS.2026.0050s

[Abstract] (3) [PDF 1.70 M] (24)

Abstract:
Molybdenum (Mo) is used as a first-wall material in EAST, where laser-induced breakdown spectroscopy (LIBS) is a promising tool for in-situ diagnostics of plasma-wall interactions (PWIs). The large variation in ambient pressure during EAST operation can significantly affect the expansion of laser-ablated plasmas and, consequently, the stability of LIBS signals. In this study, plasma emission spectra were recorded in coaxial and orthogonal detection geometries using a high-resolution Echelle spectrometer, and the differential Doppler shifts between the two geometries were used to investigate the pressure-dependent normal expansion velocities of Mo atoms and ions over an ambient pressure range of 4×10-5-6×102 mbar. At low pressures (4×10-5-3×10-2 mbar), Mo atoms and ions maintained relatively high expansion velocities with weak pressure dependence, reaching approximately 4-6 km/s and 11-15 km/s, respectively. Local maxima in the velocities of both species were observed near 10-1 mbar. At pressures above 1 mbar, the velocities decreased rapidly owing to enhanced collisions and confinement by the background gas. The pressure-dependent trends obtained using the Doppler-shift method agreed well with those determined by time- and space-resolved spectroscopy. These results demonstrate the applicability of Doppler-shift spectroscopy for non-contact velocity diagnostics of laser-ablated Mo plasma and provide experimental guidance for interpreting and optimizing LIBS measurements under EAST-relevant pressure conditions.

A Controllable Spatial Confinement Strategy for Modulating Laser-induced Plasma by Using Inclined Plates

Boping Xu, Junyi Liu, Mengbo Cheng, Lianzhan Wang, Jingyan Wang, Jiajia Hou, Xukun Yin, Jie Tang*, Dacheng Zhang*

DOI: 10.46770/AS.2026.0057s

[Abstract] (1) [PDF 1.60 M] (19)

Abstract:
Spatial confinement is a simple, efficient, and low-cost modulation strategy for enhancing both the signal intensity and shot-to-shot stability of laser-induced plasmas. However, achieving optimal confinement still relies on repeated experiments because existing shockwave models do not account for cavity configurations. In this work, an inclined plate confinement cavity is developed for the spatial modulation of laser-induced plasmas. The confinement effects of cavities with two typical configurations on plumes are compared and analyzed. The spectral intensities are enhanced and the shot-to-shot spectral fluctuation is reduced by using an inclined plate with an obtuse-angle configuration. The mechanism behind the disparity is demonstrated by shadowgraphs of shockwaves. A theoretical formula for the shockwave is developed by incorporating the cavity characteristic parameters into the model. The developed formula enables accurate prediction of the delay time for the reflected shockwave to propagate back to the plasma generation region in inclined plates. The predicted temporal window agrees well with time-resolved spectroscopic measurements, with a mean absolute error of 0.56 μs. Quantitative analysis of the trace element Mg is also conducted using spatially confined LIBS with inclined plates. The limit of detection of Mg is reduced to one-seventh of that with no cavity by using the inclined plate with an obtuse-angle configuration. This work provides a feasible route for controllable plasma modulation and the synergistic enhancement of plasma signal intensity and stability, facilitating precise quantitative analysis by LIBS.

Machine Learning-assisted Multimodal Spectroscopy for Rapid Quantification of NiO/YSZ and Ni/YSZ Anode Composition

Shaobo Feng, Weiran Song, Minfang Han*, Zhe Wang*

DOI: 10.46770/AS.2026.0071s

[Abstract] (3) [PDF 1.53 M] (25) [Supporting Information]

Abstract:
Conventional techniques such as X-ray diffraction and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy are commonly employed for solid oxide fuel cell (SOFC) anode characterisation to provide information on phase composition and local elemental distribution. However, these methods generally involve limited measurement coverage, relatively high analytical costs, and complex operating procedures, restricting their application to the rapid evaluation of large-area SOFC anode samples. In this work, laser-induced breakdown spectroscopy (LIBS), hyperspectral imaging (HSI), and smartphone video imaging (SVI), combined with machine learning, were applied to rapidly quantify the nominal NiO mass fraction in sintered NiO/YSZ and corresponding reduced Ni/YSZ samples. Specifically, LIBS acquired atomic emission spectra that reflected elemental information of Ni and Zr, whereas HSI and SVI recorded reflectance signals and RGB colour responses, respectively. Four regression algorithms, including partial least squares regression, locally weighted partial least squares regression, kernel extreme learning machine, and support vector regression, were employed to establish relationships between the acquired signals and nominal NiO mass fraction. LIBS exhibited the best single-modality performance, with maximum R2 values of 0.9854 and 0.9860 for the sintered and reduced samples, respectively. Further, decision-level LIBS-SVI and HSI-SVI fusion were investigated. Adding SVI improved predictive performance in most model-modality combinations, with lower RMSE values obtained in 14 of the 16 evaluated fusion cases compared with the corresponding LIBS- or HSI-based single-modality models. Overall, SVI provided useful complementary information while introducing little additional equipment cost or measurement complexity.

Repeatability -Aware Spectral Fingerprinting and Internal Separability of Nominal Metallic Material Classes by Moderate-Resolution LIBS

Nugzar Gomidze, David Jakobia

DOI: 10.46770/AS.2026.0072s

[Abstract] (5) [PDF 1.39 M] (24) [Supporting Information]

Abstract:
High spectrum-level classification accuracy in laser-induced breakdown spectroscopy (LIBS) may reflect technical-replicate dependence and acquisition-related confounding rather than generalizable material identification. This study therefore evaluates the within-specimen repeatability and internal spectral separability of nine nominal metallic material classes using a validation-aware analytical workflow. The dataset comprised 181 single-shot spectra obtained from nine physical specimens, with one specimen representing each nominal class. Repeatability descriptors, principal component analysis, Ward hierarchical clustering, and random forest classification were combined with label-permutation testing, acquisition-metadata analysis, and leave-one-acquisition-signature-out assessment. Mean within-class spectral correlations ranged from 0.745 to 0.971, and the first two principal components explained 63.55% of the total variance. random forest out-of-bag resampling completely separated the technical-replicate spectra, whereas weighted accuracy decreased to 93.37% when complete acquisition signatures were excluded. Acquisition metadata predicted material class above chance, and the association between material class and acquisition signature was statistically significant. Label permutation produced a mean null accuracy of 11.18% and an empirical p-value of 0.00498, confirming non-random internal spectral structure. The results demonstrate internal separability among the measured specimens but do not establish identification performance for independently acquired materials. The principal contribution is a transparent validation-aware framework that distinguishes within-dataset separation from external material identification and identifies independent multi-specimen testing under uniform acquisition conditions as the necessary next step.

Data-provenance-aware Stark Broadening Estimation for Automated LIBS Spectral Simulation of Ionic Lines

Yilin Wang*, Toni Aaltonen*, Shuo Zhang

DOI: 10.46770/AS.2026.0075s

[Abstract] (9) [PDF 1.31 M] (18)

Abstract:
Laser-induced breakdown spectroscopy (LIBS) simulation requires accurate Stark-width parameters, yet reliable data remain missing for many spectral lines. Current simulators rely mainly on manually maintained tables, simplified analytical formulas, or the STARK-B database — but manual curation is labor-intensive, simplified formulas carry large errors, and STARK-B covers a limited set of lines on a discrete, pre-computed temperature grid. To bridge these gaps, an automated ion-line Stark-width workflow was developed based on the modified semi-empirical (MSE) method on top of the NIST Atomic Spectra Database, with the required oscillator strengths completed through a tiered hierarchy of sources. The MSE formalism is defined for ionized emitters, and the workflow inherits that domain. Each computed width is returned with an uncertainty estimate and a full data-provenance trace, and widths resting on weak inputs are automatically flagged as high-risk. The workflow is accessible through both a web interface and a Python SDK, making Stark widths available at the scale that spectrum-level LIBS applications require. The workflow is validated against two independent references: the semiclassical STARK-B database and the critically evaluated measured widths of Konjevi? et al. (2002). The MSE formalism itself, applied with hand-curated inputs, carries a stated accuracy of about 50 %; the automated workflow trades part of this precision for coverage, since oscillator strengths are completed from external databases and statistical estimates rather than curated line by line, and sparse level data leave some widths to the approximate lumped term. Within the LIBS-relevant scope of ions II–IV in the optical window, the median ratios of computed to reference widths (W_MSE/W_ref) are 1.15 against STARK-B (802 per-condition comparisons) and 1.05 against the evaluated measurements (1,159 per-condition comparisons). Of these comparisons, 62 % and 58 % respectively fall within a factor of 1.5, and 83 % and 76 % within a factor of two. This provides the basis for obtaining Stark widths at the scale LIBS applications demand, and the identified error sources define clear routes for refining the accuracy. A dedicated treatment of the neutral emitters, the prerequisite for serving a full-spectrum LIBS simulator, is the largest single item of future work.

Spectral Acquisition-Window Optimization for FL-LIBS Quantification of Cr, Mn, and Ni in Z3CN20-09M Steel

Qi Yang, Jinna Mei, Huaiqing Qin, Yuhua Hang, Zhimin Lu, Shunchun Yao*

DOI: 10.46770/AS.2026.0076s

[Abstract] (5) [PDF 1.81 M] (17)

Abstract:
High-repetition-rate fiber-laser-induced breakdown spectroscopy (FL-LIBS) supports rapid surface scanning, yet reliable alloy quantification depends on spectra that are stable and representative of the sampled surface. Here, a spectral acquisition-window optimization strategy was developed for quantifying Cr, Mn, and Ni in Z3CN20-09M steel. Each acquisition window was characterized by pulse accumulation number and acquisition-window length, and CRITIC-TOPSIS integrated multiple spectral-quality metrics to rank the scanning conditions. Three representative acquisition windows were compared using full-spectrum partial least squares regression (PLSR) models calibrated with 11 high-alloy steel certified reference materials. The 10 ms, 4 mm s-1 condition gave the best overall performance, with a 40 μm acquisition-window length that approximately matched the laser spot diameter and a moderate pulse accumulation number of 350. Under this condition, full-spectrum PLSR yielded RMSEPs of 1.170, 0.063, and 1.975 wt.% for Cr, Mn, and Ni, respectively, lower than those under the matched comparison conditions. Subsequent model optimization using mutual information-variable importance in projection PLSR (MI-VIP-PLSR) further reduced the RMSEPs to 0.552, 0.047, and 0.127 wt.%. MI-VIP retained compact subsets of chemically informative variables, improving model interpretability while preserving high prediction accuracy. These results link pulse accumulation and spatial sampling to quantitative accuracy and provide a physically interpretable strategy for rapid, reliable FL-LIBS alloy quantification.

Identification of Special Steel Types by LIBS Using Iterative Wavelet Transform Combined with Deep Boltzmann Machine and Backpropagation Neural Network

Zhihui Tian, Xing Cai, Yi feng Tian, Zixuan Shen, Yang Shu, Jiuling Meng*, Juhong Tong, Yang Zhao, Junxiao Wang, Qingdong Zeng*, Huaqing Yu

DOI: 10.46770/AS.2026.0027s

[Abstract] (6) [PDF 2.41 M] (90)

Abstract:
Specialty steel is an essential foundational material for equipment manufacturing and large-scale engineering projects. For efficient, rapid and accurate classification and identification of specialty steel, this work proposes a cascade laser-induced breakdown spectroscopy (LIBS) classification model combining the iterative wavelet transform (IWT) and deep Boltzmann machine–backpropagation neural network (DBM-BP). This study investigates seven types of special steel. Initially, the spectral data were subjected to background removal using IWT. Subsequently, principal component analysis (PCA) and DBM were respectively employed to reduce the dimensionality of the preprocessed data. Finally, two hybrid classification models, namely, PCA-BP and DBM-BP were constructed. The experimental results revealed that the signal-to-background ratio (SBR) of the Mn element increased by approximately one order of magnitude after IWT background removal. Furthermore, the DBM-BP model achieved a classification accuracy of 98.53 % on the training set and 96.83 % on the test set for the specialty steel samples, validating the superiority of the DBM-BP model in nonlinear feature extraction. This study demonstrates that the IWT-DBM-BP combined model effectively suppresses the continuous background while preserving critical spectral features, thereby enabling high-precision classification. within the seven types of specialty steel samples investigated. This study offers reliable technical support for practical LIBS applications in rapid steel identification and intelligent scrap metal sorting.

GIGED-1pro: Bridging Instrumentation and Discovery in Nanocrystal Crystallography for Planetary and Terrestrial Materials

Haiyang Xian*, Jianxi Zhu*, Wenlin Yang, Fuxin Huo, Yiping Yang, Xiaoju Lin, Hongping He

DOI: 10.46770/AS.2026.0068i

[Abstract] (10) [PDF 6.18 M] (88)

Abstract:
Three-dimensional electron diffraction (3DED) has evolved into a mainstream method for nanocrystal structure determination, with widespread applications in structural biology, pharmaceutical research, functional materials, and Earth and planetary sciences. Here we report GIGED-1pro (Guangzhou Institute of Geochemistry Electron Diffractometer, first generation, professional version), a self-developed dedicated instrument for rapid nanocrystal structure determination. The instrument comprises a 120 kV Schottky thermal field emission gun as the electron source, a vertical column geometry, a 4-axis goniometer stage (drift < 200 nm over a ±50° tilt range), and a Dectris Quadro hybrid pixel direct electron detector. It integrates TEM imaging, continuous rotation electron diffraction (cRED) acquisition, and an automated data processing pipeline. Single-crystal structure determination of natural fluorapatite and calcite confirms that the instrument is capable of de novo structure solution of submicrometer mineral crystals. Batch phase screening was validated using Chang’e-6 lunar regolith as a complex unknown system. Unsupervised hierarchical clustering of 43 valid diffraction datasets successfully identified six mineral phases: cristobalite, clinopyroxene, olivine, andesine–labradorite, anorthite, and ilmenite. No priori phase assumption was required, and only trace powder was dispersed on a TEM grid. These results demonstrate that GIGED-1pro, through its dedicated and integrated design, achieves full-workflow coverage from nanocrystal structure determination to unbiased batch phase screening for mineralogical samples, demonstrating potential as an effective tool for low-consumption structural characterization of precious extraterrestrial returned samples and deep-Earth nanominerals. Its core design as a general-purpose nanocrystal electron diffraction platform may potentially be applicable to structural biology, pharmaceutical development, and functional materials research, though experimental validation in these additional fields remains for future work.

Effects of Particle Size and Digestion Protocol on Trace Element Determination of the GPt-5 Chromite Reference Material

Junjie Xu, Wen-Jun Hu*, Zhuyin Chu, Peng-Fei Zhang, Hongyu Zhang, Yifan Yin, Shao-Li Wang, Hai-Tao Li, Huan Jennifer Chang, Liang Qi

DOI: 10.46770/AS.2026.0045

[Abstract] (9) [PDF 1.29 M] (139)

Abstract:
Chromite is an important mineral for understanding igneous processes because it preserves primary geochemical signatures of mafic and ultramafic magmas. Trace elements in chromite, particularly the first-row transition elements (e.g., Co, Ni, Zn, and Mn) and Ga, provide important constraints on magma evolution processes. Development of chromite reference materials for LA-ICP-MS analysis commonly relies on acid digestion followed by solution ICP-MS analysis. However, chromite is a refractory mineral and may not be completely dissolved under conventional acid digestion conditions, which could potentially affect the accuracy of reference values. In this study, we evaluate the effects of apparent digestion efficiency on trace element analysis of the chromite reference material GPt-5. Four experimental groups were designed by combining two powder grain sizes (fine and ultrafine) with two digestion protocols (HF–HNO? digestion and aqua regia-assisted digestion). The results show that ultrafine grinding significantly improves visible digestion efficiency. However, despite these differences in digestion appearance, the four experimental groups yield broadly consistent concentrations for the first-row transition elements and Ga. These results indicate that incomplete digestion has only a limited effect on the final determination of most trace elements in chromite. This study also provides additional trace element measurements for the GPt-5 reference material, which are generally consistent with previously reported INAA recommended values, except for Zn, which shows systematically higher concentrations in the present study.

High-Precision Cesium Quantification in Kelp via Dual-Modal Spectral Fusion with an Out-of-Fold Error-Driven Weighting Strategy

Xiaoliang Liu, Junyu Mo, Min Zhang, Jingrong Li, Mengjia Zhang, Chao Xiong, Rong Hua*, Xinglei Zhang*, Debo Wu, Xiangfeng Liu

DOI: 10.46770/AS.2026.0064s

[Abstract] (10) [PDF 2.02 M] (108) [Supporting Information]

Abstract:
Kelp exhibits significant bioaccumulation for cesium (Cs) in seawater, making accurate Cs determination critical for marine monitoring and seafood safety. To overcome the inability of individual LIBS or XRF techniques to simultaneously ensure high accuracy and stability across the ultra-wide range of 500–50,000 ppm, this study proposes a concentration-sensitive dual-modal adaptive weighted feature fusion (WFF) strategy. The method employs interval-independent cross-validation to estimate the true generalization error of each modality within distinct concentration intervals, and introduces an auxiliary discriminator to guarantee accurate interval assignment for unknown samples under blind testing. The error-driven Softmax weighting module adaptively allocates feature weights, achieving optimal synergy by leveraging LIBS at low concentrations and XRF at medium-to-high levels. Validation on five independent test samples yields an RMSEP of 803 ppm, an ARE of 4.98%, and an average RSD of 6.78%, all of which significantly surpass the results from single-modality models, data-level fusion (DF), and fixed-weight feature fusion (FF). Comparative feature selection analysis reveals that the joint screening in DF suffers from statistical partiality, allocating excessive variables to XRF background spectra and systematically omitting the target Cs line and coexisting elemental lines in LIBS. In contrast, independent selection precisely preserves critical physical features from both sources. By implementing interval-independent validation-driven weight allocation, this work achieves synergistic enhancement of accuracy and stability over an ultra-wide concentration range, providing a robust and effective pathway for multimodal spectral fusion analysis of complex matrix samples.

Multi-Element 2D and 3D Picosecond LIBS Imaging of Steel Segregation Using a Sagittal-Focused Multiband Spectrometer

Zixiong Qin, Shoujie Li, Qun Yan, Yudai Hase, Zhenzhen Wang, Yoshihiro Deguchi*

DOI: 10.46770/AS.2026.0056s

[Abstract] (12) [PDF 1.40 M] (131)

Abstract:
The inherently destructive nature of laser-induced breakdown spectroscopy (LIBS) precludes repeated sampling of the same surface region, rendering simultaneous multi-element acquisition essential for LIBS elemental mapping. In this study, a picosecond LIBS mapping system was integrated with a custom-developed sagittal-focused multiband spectrometer to achieve simultaneous multi-element two-dimensional (2D) and three-dimensional (3D) microanalysis of segregation in steel samples. The sagittal-focused optical design efficiently concentrates spectral signals onto the effective detection window of linear array detectors, enabling reliable single-shot spectral acquisition under the weak-signal conditions inherent to high-spatial-resolution mapping. Operating at a spatial resolution of 2 μm, the system simultaneously captured emission lines of four critical alloying elements, Al, Cu, Ti, and Mn, across two spectral channels in a single mapping scan. For 3D microanalysis, a defocus-focused coordinated scanning strategy enabled 12-layer depth-resolved elemental imaging within a volume of 100 × 100 × 24 μm3 with stable signal quality across all layers. These results demonstrate that integrating sagittal-focused multiband detection with picosecond LIBS mapping provides a comprehensive and practically irreplaceable tool for simultaneous, multi-element microstructural characterization of steel segregation.

Quantitative Hydrogen Analysis in Humid Atmospheric Environments with Spark-Discharge Assisted LIBS Using a Microchip Laser

Tao Zeng, Zenghui Wang, Cong Yu, Yufeng Li, Runhua Li, Yuqi Chen*

DOI: 10.46770/AS.2026.0058s

[Abstract] (10) [PDF 1.36 M] (125)

Abstract:
In-situ, rapid and sensitive hydrogen leak monitoring in confined spaces remains challenging because air humidity can affect the accuracy and sensitivity of hydrogen detection. In this work, a compact spark-discharge-assisted laser-induced breakdown spectroscopy (SD-LIBS) system based on a microchip laser was developed for rapid quantitative hydrogen analysis in humid air. Spark discharge significantly enhanced the emission of the microchip laser-induced plasma. To improve the measurement reliability, the Ar I 794.82 nm line was employed as a primary in-spectrum reference for spectral normalization, while the N I 746.83 nm line was subsequently used as a secondary air-derived reference to improve the robustness of hydrogen quantification against variations in the local gas environment. In addition, humidity-dependent background correction was applied to reduce the contribution of water vapor to the Hα emission. Quantitative measurements were performed on hydrogen concentrations ranging from 0.5% to 3.5% at relative humidity between 32% and 74%. Compared with direct background subtraction, the combined Ar I normalization and N I-based secondary correction strategy obviously improved the linearity of hydrogen quantification, yielding calibration curves with R2 values above 0.980 and a maximum value of 0.993 at 66% relative humidity. The estimated limit of detection for hydrogen was determined to be 941 ppm. These results demonstrate that the proposed microchip-laser-based SD-LIBS method with humidity-dependent correction enables improved calibration linearity for hydrogen analysis and shows potential for early hydrogen leak detection in humid atmospheric environments.

OTTO-WDID-Based Class-Specific Variable Selection and Sequential Threshold-Rule Classification for Multiclass LIBS Modeling of Edible Salt Products

Sandeep Kumar, Vivek K. Singh, Sang-Ho Nam, Song-Hee Han, Yonghoon Lee*

DOI: 10.46770/AS.2026.0053s

[Abstract] (10) [PDF 1.67 M] (199)

Abstract:
Laser-induced breakdown spectroscopy (LIBS) provides rapid elemental fingerprints, but multiclass classification often requires both interpretable variable selection and a transparent classification rule. In this study, we propose a combined framework that links one-to-the-others wavelength-dependent interclass distance (OTTO-WDID) with sequential threshold-rule classification. OTTO-WDID evaluates each wavelength by comparing one target class with all remaining classes, thereby identifying class-specific emission lines suitable for one-to-the-others decisions. A local baseline-drift correction was applied using adjacent non-emission wavelengths to estimate the emission-line-specific contribution to the observed interclass distance. The framework was applied to LIBS spectra of five edible salt products. OTTO-WDID identified the emission peaks of Ba II at 455.4 nm, Si I at 288.2 nm, Ca I at 612.2 nm, Sr II at 407.8 nm, and Li I at 670.8 nm as class-specific variables for the corresponding sample classes (S1 – S5, respectively). These variables included weak trace-element lines, showing that highly discriminative information is not necessarily associated with the strongest emission peaks. The selected variables were then used to construct a sequential threshold-rule classifier, in which each step separates one target class from the remaining classes using a single class-specific variable and threshold. For the five-class problem, only four active threshold rules were required because the final class was assigned as the residual class. The least reliable Ba II variable was excluded from the active rule sequence, and S1 was assigned as the residual class. Using the sequence S2 → S3 → S4 → S5 → S1, the classifier achieved 100% accuracy in leave-one-out cross-validation. The results demonstrate that OTTO-WDID and sequential threshold-rule classification provide a simple, interpretable, and compact pipeline for multiclass LIBS modeling.

Development and Application Validation of a Molten Steel Composition Sensor Based on Laser-Induced Breakdown Spectroscopy

Yang Zhou, Lanxiang Sun*, Changjiang Ding, Guocai Wang, Zhengsheng Chang, Yang Li, Cong Zhang, Peng Zhang

DOI: 10.46770/AS.2026.0039s

[Abstract] (14) [PDF 2.24 M] (238)

Abstract:
The practical application of spectral sensors for molten steel composition online detection has remained limited due to the combined effects of extreme temperature, slag erosion, and transmission challenges associated with weak emissions from trace elements. In this study, a molten steel composition sensor was developed based on Laser-Induced Breakdown Spectroscopy (LIBS). The sensor incorporates a 1.5-meter-long multi-layered probe lance through which the laser beam is focused onto molten steel at the lower end, where the emitted plasma is analyzed to enable online composition measurement. During operation, the probe lance penetrates through the slag layer and maintains immersion in molten steel at a certain depth withstanding temperature exceeding 1650°C. Both the probe lance and the entire optical return path are purged with argon gas to enhance the signal. Through the acquisition of optimal parameters, the industrial application was first performed? using the LIBS sensor? during the refining of 120-ton molten steel. Test set demonstrates R2 of 0.9361, 0.9643, 0.9809, and 0.9815 with corresponding RMSE of 0.04wt.%, 0.03wt.%, 0.03wt.%, and 0.07wt.% for C, Mn, Si, and Cr respectively. Results indicate that the LIBS sensor has preliminarily achieved in-situ online detection of specific elements in molten steel, showing promising application potential.

A Homologous Detection Strategy Based on Spectrum-ultrasound-image for Precise Analysis in Coal LIBS

Xuechen Niu, Feiyu Guan, Yongtai Zhuang, Haineng Yang, Deng Zhang, Junfei Nie, Jianguo Liu, Zhenlin Hu*, Lianbo Guo*

DOI: 10.46770/AS.2026.0018s

[Abstract] (41) [PDF 1.11 M] (403) [Supporting Information]

Abstract:
Coal analysis plays a crucial role in its efficient utilization and pollution control. Laser-induced breakdown spectroscopy (LIBS) exhibits promising application prospects in coal quality analysis because of its uniquely rapid and minimally destructive capabilities. However, the complex composition of coal induces severe matrix effects, which pose a formidable challenge to the accurate quantification in traditional LIBS analysis. In this study, a novel method named spectrum-ultrasound-image multi-modal fusion model (SUI-MM) was introduced to mitigate matrix effects in coal and improve the quantitative performance. SUI-MM extends conventional LIBS to a homologous multi-modal analysis framework combining spectra, ultrasound, and image, effectively compensating for the absence of physical structural and plasma spatial morphological information in spectra. By establishing a three-dimensional feature extraction and fusion strategy, it enables comprehensive characterization of coal plasma behavior and further improves quantitative performance. To verify the effectiveness of SUI-MM, experiments were performed on elemental and proximate analysis of coal. For the elemental analysis, the average R2p is improved to above 0.998, while RMSEp and AREp are reduced by 88% and 90%, respectively. For the proximate analysis, the average R2p is increased to over 0.999, and both RMSEp and AREp are decreased by 91% on average. Furthermore, ablation experiments confirm that image and ultrasonic signals contribute significantly to the improved analytical performance. These results demonstrate that the SUI-MM scheme can effectively mitigate matrix effect and significantly improve the quantitative accuracy in coal. In summary, SUI-MM is expected to further support the low-carbon transition of the energy industry.

LIBS Analysis of Laser-ablated W Plasma at Variable Ablation Angles and Gases in Low-pressure Atmospheres

Boliang Men, Cong Li*, Huace Wu, Shiming Liu, Gaogui Feng, Zhihang Li, Longfei Li, Dongpeng Tian, Ding Wu, Ran Hai, Xingwei Wu, Hongbin Ding

DOI: 10.46770/AS.2026.0004s

[Abstract] (42) [PDF 2.30 M] (342) [Supporting Information]

Abstract:
Laser-induced breakdown spectroscopy (LIBS), as an in situ and real-time diagnostic technique, has proven effective in acquiring elemental distribution information under extreme operational conditions. Under the actual operating conditions of tokamak devices, the ablation angle and gas atmosphere exert a synergistic influence on the evolution behavior of laser-ablated plasma. However, the underlying physical mechanisms have not yet been fully elucidated, necessitating more systematic and in-depth investigations. The LIBS characteristics of laser-ablated W plasma under low-pressure (100 Pa) Ar, He, N2 gases and various incident angles were systematically investigated. LIBS spectra revealed that at low laser energy density, Ar promotes more effective electron collision excitation and plasma recombination, while the higher thermal conductivity of He facilitates free expansion of the plasma. In N? atmosphere, the signal-to-background ratio (S/B) of laser-ablated W plasma remained largely independent of the angle, which aids in optimizing LIBS signal stability. As the laser-ablated angle increases, the laser energy density decreases, leading to reduced stability and symmetry of the plasma plume. Further research indicates that as laser energy density decreases, the axial expansion of the W plasma plume remains nearly unchanged, whereas the radial expansion decreases rapidly. This study elucidates the evolution mechanism of the laser-ablated W plasma under the synergistic effects of ablation angle and gas atmosphere. The results provide an important theoretical basis for the geometric calibration and optimization of in situ LIBS diagnostic systems intended for operation under low-pressure conditions.

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Invited Review

Review: Tracking Lithium Ion Transport in All-solid-state Batteries Using Neutron Depth Profiling

Caijin Xiao*, Junwei Liang*, Liang Zhao, Jiawang Meng, Ming Liu*

2026,47(4),486-498,

DOI: 10.46770/AS.2026.0019i

[Abstract] (50) [PDF 4.31 M] (527)

Abstract:
Neutron depth profiling (NDP) is a non?destructive, operando technique that directly quantifies lithium distribution and transport in all?solid?state batteries (ASSBs) by exploiting the 6Li(n, α)3H nuclear reaction. Conventional techniques (e.g., X?ray methods) rely on interactions with extranuclear electrons and thus struggle to detect lithium due to its low electron density. By contrast, NDP exploits the direct nuclear reaction, enabling unambiguous localization of 6Li atoms. Consequently, NDP provides quantitative, depth?resolved monitoring of lithium concentration profiles along the battery thickness direction with a typical depth resolution of tens of nanometers. This review systematically summarizes recent progress in applying NDP to four key aspects of ASSBs: electrolytes, electrodes, interfaces, and thin?film full batteries. In electrolytes, NDP has revealed electronic?conductivity?induced random dendrite nucleation and reversible short?circuit phenomena. In electrodes, it has guided 3D framework designs, validated surface halogenation for Si anodes, and verified longitudinal Li gradients in composite cathodes. In interfaces, NDP has visualized space?charge layers, quantified lithiophilic coating effects, and provided early detection of short?circuit failure. In thin?film batteries, NDP has tracked Li?ion transport in near real time using isotopic tracers, identified Si migration as a degradation mechanism, and pinpointed rate?limiting interfaces in combination with other techniques. Beyond these applications, the inherent advantages and current limitations of NDP—such as its sensitivity to 6Li isotope, the trade?off between depth resolution and counting statistics, and the requirement for flat sample surfaces—are critically discussed. This review establishes NDP as an indispensable tool for understanding and engineering lithium transport in ASSBs, and outlines future directions including higher?flux neutron sources, improved detector systems, and integration with complementary in situ probes.

Article

Quasi-Non-Destructive Multi-Element Characterization of Polymer Materials for 3D-Printed Firearms by Liquid Microjunction Sampling into Inductively Coupled lasma Mass Spectrometry (LMJ-ICPMS)

Jordan Chiabai, Diane Beauchemin*

2026,47(4),499-506,

DOI: 10.46770/AS.2026.0061

[Abstract] (38) [PDF 604.17 K] (254) [Supporting Information]

Abstract:
In this proof-of-concept study, liquid microjunction inductively coupled plasma mass spectrometry (LMJ-ICPMS) was used as a localized, quasi-non-destructive approach for the qualitative trace elemental characterization of polymer materials relevant to forensic investigations involving 3 dimensions (3D)-printed firearms. Blue nylon glass-fibre-reinforced polyamide 6 (PA6-GF), polyethylene terephthalate glycol (PETG), and polylactic acid (PLA) were analyzed using a custom LMJ sampling interface coupled to quadrupole-based ICPMS. Measurable transient signals were obtained for multiple elements directly from polymer surfaces, demonstrating the capability of LMJ sampling to recover and transport trace elemental constituents with minimal sample preparation and limited surface disruption. Distinct normalized elemental profiles were observed between PA6-GF and PETG, with PETG exhibiting higher relative abundances of Mg, Ca, Ti, and Sr, whereas PA6-GF exhibited elevated Ba. Complete separation between PA6-GF and PETG was achieved using Ti/Mg and Ba/Ca elemental ratios, while targeted and untargeted principal component analyses demonstrated distinct clustering based on selected elemental markers and the broader elemental profile, respectively. The first two principal components of the targeted analysis accounted for 97.7% of the total variance. Addition of 2% (v/v) methanol (MeOH) to the 2% (v/v) nitric acid (HNO3) sampling solvent improved elemental recovery of PLA, enabling multivariate differentiation of PA6-GF, PETG, and PLA, with the first two principal components accounting for 97.0% of the total variance. These results demonstrate the applicability of LMJ-ICPMS for qualitative elemental profiling and differentiation of polymer materials, while highlighting the importance of solvent optimization for extending the approach to chemically distinct polymer systems.

Accurate and Rapid Determination of 99Tc in Seawater Samples Using Triple-quadrupole ICP-MS with C2H4-He Mode

Jie Chen, Yiman Lu, Zongjie Xie, Zhilong Yang, Man Wang, Hao Wang, Jing Lin, Shan Xing*

2026,47(4),507-514,

DOI: 10.46770/AS.2026.0033

[Abstract] (24) [PDF 1.89 M] (287) [Supporting Information]

Abstract:
Accurate and rapid monitoring of 99Tc is crucial for the radiological risk assessment in nuclear emergency situations. However, accurate determination of 99Tc by ICP-MS is always hindered by the interferences of 98Mo and 99Ru. In this work, a rapid and accurate analytical method of 99Tc in seawater samples was established, and 185Re as a non-isotopic tracer was used for the monitoring of 99Tc yield in the whole procedure. TiCl3 was chosen as a reducing agent and co-precipitant for the 99Tc preconcentration. 98Mo and 99Ru were effectively removed using two TK200 resin columns under novel alkaline loading conditions, and the excellent decontamination factors (DFs) of 4.28 × 106 for Mo and 5.16 × 105 for Ru were achieved. Importantly, the interferences of 98Mo+ tailing, 99Ru+ and 98Mo1H+ can be efficiently suppressed using C2H4 as a new reaction gas for 99Tc measurement, and 98Mo1H+/98Mo+ of 1.31 × 10?7 was achieved at 0.28 mL/min C2H4-1.0 mL/min He. The overall decontamination factor of Ru reached 3.76 × 107, which are at least 2 orders of magnitude higher than that of the conventional methods. The detection limit of 3.18 pg/L (2.00 mBq/L) was obtained with a whole analytical time of 4 hours for 12 samples, which was suitable for the application of nuclear emergency. More importantly, this correction-free alternative method was found to accurately measure 99Tc by ICP-MS without any mathematical correction of 99Ru for the first time.

Determination of Radioactive Selenium-79 in Environmental Samples by ICP-MS after Solid Phase Microextraction - Dielectric Barrier Discharge Vapor Generation

Zhenqi Gao, Shanshan Chen, Zenghui Zhu, Junrong Wang, Shengkang Liang, Qian He*

2026,47(4),515-525,

DOI: 10.46770/AS.2026.0038

[Abstract] (15) [PDF 992.95 K] (265) [Supporting Information]

Abstract:
Accurate determination of 79Se level in environmental samples is critical for evaluating radioactive contamination risk. A new pretreatment method for 79Se determination by inductively coupled plasma-mass spectrometry (ICP-MS) through solid phase microextraction (SPME) - dielectric barrier discharge vapor generation (DBDVG) - ammonia water absorption-evaporation (AAE) was proposed in this work. The sorbent of nano-ZrO2 was used in SPME, which could both enrich Se and selectively adsorb Se from Br, which has an identical mass of 79 to 79Se. DBDVG was used to reduce the species of Se from Se(IV) or Se(VI) to volatile H2Se vapor to eliminate the sample matrix interferences. Ammonia water was used to absorb the volatile H2Se and then evaporated to enrich Se. The adsorption, DBDVG and absorption parameters were optimized in detail. The mass interference of 38Ar40ArH+ was effectively eliminated by the addition of He gas in the collision/reaction cell, and the other potential interferences of 39K40Ar+, 63Cu16O+, 158Gd2+, 158Dy2+ and 78SeH+ were all not obvious in this method. The detection limit of 79Se was 10.1 ng L-1 and the inter-batch reproducibility between different SPME tubes was 1.9 %. The concentration of 79Se in environmental samples such as lake water and plant leaves were assessed. Compared with conventional ion exchange resin methods for enrichment of 79Se, our SPME approach achieves desorption via DBD plasma without the need of acidic or alkaline reagent for elution. In contrast to conventional ICP-MS sample introduction methods for ??Se determination, such as hydride generation and electrothermal vaporization, the proposed DBDVG technique drives redox reactions entirely via free radicals and electrons generated in the discharge plasma. This design fully eliminates the need for additional redox reagents or chemical modifiers, and thus drastically lowers the associated reagent blank levels.

Comparative Evaluation of a Novel Lithium Metaborate Fusion Approach and Phosphate Fusion for Multielement ICP‑OES Analysis of Nb–Ta Ores

Lucie ?imoníková, Lubomír Proke?, Jan Loun, Viktor Kanicky, Karel Novotny*

2026,47(4),526-537,

DOI: 10.46770/AS.2026.0042

[Abstract] (20) [PDF 1.06 M] (302) [Supporting Information]

Abstract:
Reliable determination of niobium and tantalum in Nb–Ta ores is analytically challenging due to the refractory nature of the matrix and pronounced spectral and matrix effects in ICP?OES. In this study, two chemically distinct fusion procedures – an established phosphate fusion and an optimized lithium metaborate (LiBO2) fusion followed by dissolution in a dilute HF/HNO3 mixture – were systematically compared. A dataset of 69 natural Nb–Ta mineral concentrates and one industrial synthetic material analyzed over a ten-year period was used for the comparison. Method equivalence was assessed using Deming regression with a heteroscedastic error structure. Trueness was evaluated using the CRM X1808 certified reference material and an in-house reference material characterized by X-ray fluorescence (XRF). Both fusion methods provided analytically equivalent results for Nb2O5 and Ta2O5 across the entire concentration range. However, borate fusion allowed simultaneous determination of a broader range of elements, including Na2O, P2O5, and SiO2. Although both approaches can be used to quantify most analytes, their applicability is partly complementary: phosphate digestion does not allow reliable determination of sodium and phosphorus, and SiO2 determination may be limited at higher concentrations. In addition, while both fusion techniques are considerably more rapid and more robust than conventional acid digestion, borate fusion also allows slightly faster sample preparation. Overall, fusion-based approaches represent an efficient and reliable strategy for the comprehensive analysis of complex Nb–Ta matrices.

Spatiotemporal DVS Event-stream Fusion for Robust LIBS Contamination-level Classification under Laser-energy Perturbation

Hongyu Wang, Tao Deng, Weiliang Liu, Bin Cao, Honglin Jian, Junchen Li, Lei Deng, Xilin Wang*

2026,47(4),538-554,

DOI: 10.46770/AS.2026.0035

[Abstract] (29) [PDF 5.76 M] (344)

Abstract:
Laser-induced breakdown spectroscopy (LIBS) is promising for rapid contamination analysis of power insulators, but its reliability is limited by laser-energy perturbation during field detection. To improve the robustness of LIBS-based contamination-level classification, this study proposes a LIBS–DVS Hybrid Gated Fusion Spiking Neural Network (LD-HGF-SNN) by integrating LIBS spectra with raw dynamic vision sensor (DVS) event streams. Unlike methods based on reconstructed event images, LD-HGF-SNN constructs a raw-event-derived spatiotemporal DVS event tensor to preserve the time–height–width evolution of laser-induced plasma and encodes it using an LIF-neuron-based spiking branch. A 1D convolutional branch extracts LIBS spectral features, while a sample-adaptive gated fusion module regulates the contributions of spectral and event-stream information. Broad-energy classification and cross-energy evaluation tasks were constructed using paired LIBS–DVS data collected under seven laser-energy conditions. LD-HGF-SNN achieved 97.50% accuracy and 97.49% macro-F1 under the reference-energy condition, and maintained 87.50% accuracy and 87.52% macro-F1 under full-range laser-energy perturbation. In the most challenging task, its accuracy exceeded the strongest ablation model, the ungated fusion model, and the reconstructed-image fusion baseline by 15.50, 21.00, and 22.50 percentage points, respectively. These results indicate that raw-event-derived DVS event streams provide complementary plasma-dynamic information for LIBS spectra, and that preserving the spatiotemporal structure of DVS events can improve LIBS classification robustness under laser-energy perturbation.

From Site Assessment to Simulated Experiment: A Parallel Investigation of Heavy Metal Pollution in a Soil-Taraxacum mongolicum Hand.-Mazz. System Impacted by Tungsten-Beryllium Mining in Haba Snow Mountain

Ning Lu#, Linjun Zhang#, Xiaofang Yang, Jiayi Hu, Xin Liu, Xiangdong Yu*, Xiaodong Wen*

2026,47(4),555-573,

DOI: 10.46770/AS.2026.0048

[Abstract] (34) [PDF 6.77 M] (312) [Supporting Information]

Abstract:
Accurate detection and systematic assessment centered on atomic spectrometry techniques serve as an essential foundation for elucidating the pollution characteristics, ecological risks, and health hazards of heavy metals (HMs) farmland soils around mining areas. In this study, inductively coupled plasma optical emission spectrometry (ICP-OES) was employed as the core analytical technique to precisely quantify ten HMs in farmland soils approximately 20 km from a tungsten (W) beryllium mining area. Based on the measured ICP-OES data, GIS visualization was integrated with the geo-accumulation index (Igeo), pollution load index (PLI), potential ecological risk index (PERI), human health risk assessment (HHRA), and positive matrix factorization (PMF) source apportionment model to systematically evaluate the pollution characteristics, risk levels, and source contributions of HMs in the farmland. Meanwhile, the stress effects of W on Taraxacum mongolicum Hand.-Mazz. (T. mongolicum) were investigated through a pot experiment under W stress. The comprehensive pollution assessment revealed that the Igeo values of Cd, W, and As reached 3.88, 3.76, and 3.51, respectively, all indicating heavy contamination, and the PLI values corresponded to heavy to extremely heavy pollution levels. PMF identified five pollution sources. HHRA indicated that all population groups faced both carcinogenic and non-carcinogenic risks, with children exhibiting the most pronounced risks and direct ingestion serving as the primary carcinogenic exposure pathway. The pot experiment demonstrated that, under W stress, HMs accumulation capacity followed the order: roots > leaves, whereas the content of active components exhibited no significant change. This study validates the effectiveness and reliability of ICP-OES in the precise quantification of soil HMs and environmental risk assessment, providing a reliable data foundation and methodological support for the comprehensive assessment, prevention, and control of HM pollution in farmland soils.

Quantitative Analysis of Microstrain and Investigation of Microscopic Mechanism Based on Laser-Induced Breakdown Spectroscopy

Shuoyu Yang, Yazi Wang, Yongyi Du, Jiaqi Zhao, Yue Lv, Xiaoning Yang, Yifan Luo, Ruibin Liu*

2026,47(4),574-584,

DOI: 10.46770/AS.2026.0055

[Abstract] (5) [PDF 2.81 M] (223) [Supporting Information]

Abstract:
The microstructure of metallic materials, particularly their strain characteristics, constitutes the core determinant of macroscopic physicochemical properties; therefore, achieving rapid, precise, and in-situ characterization of microstructure is important for research on metallic materials. Since the microstructure of materials can modulate plasma excitation conditions, microstrain information in metallic materials can be reflected through plasma emission spectra. Laser-induced breakdown spectroscopy (LIBS) has been conventionally employed for detecting elemental composition and conducting quantitative analysis of elemental content; however, investigations of microstrain based on LIBS remain unreported. In this study, we, for the first time, utilized spectroscopic information from laser-induced plasma to establish a classification model for microstrain. Furthermore, by integrating artificial intelligence algorithms, we constructed a quantitative relationship model between spectral characteristics and microstrain, thereby realizing online in-situ quantitative analysis of microstrain. We also conducted an in-depth investigation into the influence mechanism of microstructure on plasma spectra, providing a solid theoretical and experimental foundation for rapid diagnosis of material microstrain based on LIBS technology.

Direct Determination of 206Pb/204Pb and 208Pb/204Pb Ratios by Triple Quadrupole ICP-MS Without Pb Purification: Opportunities and Limitations for Source Tracing

Yangjunjie Xu-Yang*, Sophie Ayrault, Delphine Thomas

2026,47(4),585-594,

DOI: 10.46770/AS.2026.0047

[Abstract] (13) [PDF 5.07 M] (289) [Supporting Information]

Abstract:
Lead stable isotope ratios 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb are widely used to trace the origin of natural or artificial materials in geochemistry, environmental science and archaeology. Time consuming sequential column chemistry for purification of Pb are often necessary for preparing the analysis of Pb isotopes ratios with MC-ICP-MS, with a precision (uncertainties) reaching 0.001. However, such a high precision is not always necessary for source tracing when the end-members have significant different signatures. Here, 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios were analyzed for 7 certified reference materials (CRM: SL-1, RGM-1, MAG-1, BHVO-1, BCR-723, BCR-1 and BCR-2), including sediments and urban road dusts, using Triple Quadrupole Inductively Coupled Plasma Mass Spectrometry (TQ-ICP-MS) after conventional total digestion without sequential column chemistry. The solutions from the digestion were measured at four Pb concentrations (0.5, 1, 1.5 and 2 ng ml-1). Among 56 measurements on 33 SL-1 samples at a lead concentration of 2 ng ml-1 (sample digestion was realized between 2018 and 2024 while lead isotopic ratio measurements were conducted between 2022 and 2025), the first and third quartile of the uncertainties are 0.07 and 0.1 for 206Pb/204Pb, 0.05 and 0.09 for 207Pb/204Pb and 0.16 and 0.21 for 208Pb/204Pb. The 206Pb/204Pb and 208Pb/204Pb ratios obtained with TQ-ICP-MS can be especially useful for source tracing while uncertainties related to 207Pb/204Pb are in the same range of differences between terrestrial sources. This study employs TQ-ICP-MS to complement earlier ICP-QMS-based research, while also validating lead isotope ratio analysis using a larger set of certified reference materials (CRMs). In addition, the analytical protocol, spanning digestion and measurement over multiple years, enables an assessment of the long-term stability and reproducibility of the entire methodological workflow. We conclude that some studies can benefit from the simple and fast analysis of 206Pb/204Pb and 208Pb/204Pb ratios by TQ-ICP-MS with very small amount of additional works and investment, when potential end-members display sufficiently distinct isotopic signatures. Moreover, the here developed approach can be used to select samples which deserve more detailed geochemical analyses, lowering costs and environmental impacts.

Impurities Determination in High-purity Cerium Oxide by Aerosol Dilution ICP-MS After Solvent Extraction Separation

Shuang Zou, Shengnan Wang, Lanlan Jin, Wei Guo*

2026(4),595-600,

DOI: 10.46770/AS.2026.037

[Abstract] (10) [PDF 471.34 K] (212)

Abstract:
High-purity cerium dioxide (CeO?) powder serves as a key raw material for chemical mechanical planarization (CMP) slurries, wherein trace impurities can severely degrade its polishing efficiency and surface modification performance. This study established a reliable method for the determination of trace rare earth element (REE) impurities in high-purity (CeO?) via online aerosol dilution inductively coupled plasma mass spectrometry (AD-ICP-MS) combined with solvent extraction pretreatment. Using 2-ethylhexylhydrogen-2-ethylhexylphosphonate (EHEHP) as the extractant, the tetravalent cerium matrix was efficiently separated with a separation efficiency of ~99.8 %, and the recoveries of target REEs ranged from 92 % to 98 %. Furthermore, residual Ce-derived mass interferences on gadolinium (Gd) and terbium (Tb) detection were effectively eliminated by introducing 0.80 L min?1 argon into the sample aerosol before the ICP. Under the optimized conditions, the formation yields of interfering polyatomic ions were suppressed to as low as 0.12 % for CeO?/Ce? and 0.008 % for CeOH?/Ce?. The limits of quantification (LOQs, 10σ) for 14 REE impurities were determined to be 0.2–1.3 ng g?1. The proposed method was successfully applied to the analysis of two high-purity CeO? samples. The satisfactory spike recoveries of 93–103% verified that the proposed approach is robust and promising for the trace analysis of REE impurities in high-purity cerium oxide materials.

Laser-Induced Breakdown Spectroscopy for In Situ Analysis of Immovable Polychrome Cultural Heritage

Yikang Hou, Zhuoxi Li, Jie Lian*

2026(4),601-614,

DOI: 10.46770/AS.2026.0012

[Abstract] (12) [PDF 2.93 M] (377)

Abstract:
Immovable polychrome cultural heritage—including grotto murals, architectural wall paintings, painted plasters, and rock art—presents an analytical problem defined by three simultaneous constraints: the objects are stratified and materially heterogeneous, the key questions are usually conservation-driven rather than purely descriptive, and the investigation must be performed in situ with a level of intervention acceptable to conservation practice. In this context, laser-induced breakdown spectroscopy (LIBS) has moved well beyond its early role as a rapid elemental screening tool. Its practical significance lies in the fact that it can provide elemental information, micrometric sampling, and depth-resolved data within the same analytical sequence, thereby addressing problems that are difficult to solve by fully non-contact techniques alone, which is why depth-resolved investigation is often conservation-critical rather than merely technically attractive. This review focuses specifically on immovable polychrome heritage and examines how LIBS has been used to identify mineral pigments, disentangle repainting and overpaint, diagnose salts and surface deposits, estimate layer thickness, and support decisions on cleaning and consolidation. Emphasis is placed on the analytical logic of field deployment: acceptable micro-destructivity, parameter selection under fragile surface conditions, pulse-to-depth calibration, chemometric interpretation, and the role of multimodal workflows with Raman spectroscopy, X-ray fluorescence, optical coherence tomography, and imaging methods. Recent computational and calibration strategies—numerical simulation, machine-learning-assisted calibration, and micro-CT-aided depth calibration—are also considered as ways to reduce dependence on ideal physical standards when exact mural analogues cannot be prepared. The review argues that the present frontier is no longer whether LIBS can generate useful spectra from wall paintings, but whether its outputs can be standardized, reproduced, and translated into evidence that conservators can trust. Its long-term value therefore depends less on broadening application claims than on consolidating low-damage protocols, uncertainty-aware interpretation, and explicit integration into conservation decision-making.

Determination of Trace Copper in Biological Samples by On-line Chemical Vapor Generation-Atomic Fluorescence Spectrometry

Liang He, Xiaofan Zhu, Li Wu, Xiandeng Hou*

, DOI: 10.46770/AS.2008.03.004

[Abstract] (598) [PDF 146.88 K] (4193)

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.

Rapid Determination of Chemical Oxygen Demand by Flame AAS Based on Flow Injection On-line Ultrasound- assisted Digestion and Manganese Speciation Separation

Zhi-Qi Zhang*, Hong-Tao Yan, Lin Yue

, DOI: 10.46770/AS.2004.04.006

[Abstract] (529) [PDF 86.02 K] (4087)

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.

Determination of Cadmium at the Nanogram per Liter Level in Seawater by Graphite Furnace AAS Using Cloud Point Extraction

Chun-gang Yuan, Gui-bin Jiang*, Ya-qi Cai, Bin He, Jing-fu Liu

, DOI: 10.46770/AS.2004.04.003

[Abstract] (525) [PDF 99.16 K] (4375)

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.

Development and Validation Method for the Determination of Rare Earth Impurities in High Purity Neodymium Oxide by ICP-MS

Man He, Bin Hu*, Zucheng Jiang, Yan Zeng

, DOI: 10.46770/AS.2004.01.002

[Abstract] (573) [PDF 154.90 K] (4224)

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.

Multielement Analysis of Alkaline-Resistant Glass and Basalt Glass Fibers Using Laser Ablation ICP-MS: A Useful Tool in Technical Textile Quality Control

J. Su. Becker, C. Pickhardt, N. Hoffmann, H. H?cker, J. Sa. Becker*

, DOI: 10.46770/AS.2002.01.001

[Abstract] (681) [PDF 135.56 K] (4630)

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.

On-line Ion Exchange Preconcentration in a Sequential Injection Lab-on-valve Microsystem Incorporating a Renewable Column With ETAAS for the Trace Level Determination of Bismuth in Urine and River Sediment

Jianhua Wang, Elo Harald Hansen*

, DOI: 10.46770/AS.2001.03.003

[Abstract] (458) [PDF 167.98 K] (3902)

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.

A Sequential Injection On-Line Column Preconcentration System for Electrothermal AAS Determination of Thallium in Geochemical Samples

Zhang-Run Xu, Shu-Kun Xu, Zhao-Lun Fang*

, DOI: 10.46770/AS.2000.01.004

[Abstract] (444) [PDF 116.38 K] (3780)

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.

Trace Metals in Traditional Chinese Medicine: A Preliminary Study Using ICP-MS for Metal Determination and As Speciation

Xiaoru Wang, Zhixia Zhuang, Dahai Sun, Jiangxing Hong, Xihong Wu

, DOI: 10.46770/AS.1999.03.002

[Abstract] (634) [PDF 283.26 K] (4284)

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.

Theory, design, and operation of a dynamic reaction cell for ICP-MS

Tanner S.D.* Baranov V.I.

, DOI: 10.46770/AS.1999.02.001

[Abstract] (518) [PDF 0.00 Byte] (0)

Abstract:
Theory, design, and operation of a dynamic reaction cell for ICP-MS

Virtual Issue: Environmental Analysis in Atomic Spectroscopy for PerkinElmer, August, 2021

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