Abstract:Long half-life natural and artificial radionuclides have been paid great attention in the environment, geochronology, nuclear accidents, as well as the operation of nuclear facilities for over a decade. However, the rapid and accurate quantification of these ultra-trace level (fg or mBq) radionuclides has become a formidable challenge nowadays. A triple-quadrupole inductively coupled plasma mass spectrometry (ICP-MS) equipped with a collision reaction cell (CRC), namely ICP-MS/MS, is a valuable technique for rapid and sensitive analysis of ultra-trace level radionuclides in various kinds of samples. This article provides a comprehensive review and critical comparison of published analytical methods for ultra-trace level radionuclides in environmental, biological and nuclear waste samples. The methods of sample pre-treatment, valence state adjustment, chemical separation of radionuclides, and ICP-MS/MS measurement are systematically described and discussed. Importantly, the advantages and limitations of the collision reaction cell (CRC) technology on the removal of interferences and the radionuclide measurement are comprehensively summarized. In addition, the article also explores advancements in automated separation and measurement methodologies for radionuclides.

Abstract:Tianwen-1’s MarSCoDe payload acquires chemical compositions of Martian rocks and soils. Previous LIBS models, built with Earth-based simulated Martian spectra, face accuracy reduction due to environmental discrepancies between simulations and the real Martian surface. To address this issue, this study establishes a univariate quantitative model for major elements based on in-situ Martian MCCT LIBS spectra. The derived Root-Mean-Square Errors are comparable to those reported in previous studies, and the average elemental compositions are consistent with GRS measurements at the Tianwen-1 landing site. Based on model-derived compositions and low Chemical Index of Alteration (CIA, 21.5% ± 8.0%), most rocks and soils show overall weak chemical alteration, implying limited water–rock interactions in the Tianwen-1 landing area during the Late Hesperian to Amazonian. Nonetheless, several samples with CIA values exceeding 35% (up to 42.7%) record localized liquid water activities within the region during this period.

Abstract:Single cell inductively coupled plasma mass spectrometry (scICPMS) enables quantitative analysis of individual cells, providing access to cellular heterogeneity that is obscured in bulk analyses. However, its analytical performance is strongly constrained by sample introduction efficiency, particularly for biological cells whose transport behaviour differs from those of standard solutions and nanoparticles. In this work, an infrared (IR)–heated pneumatic sample introduction system based on a modified cyclonic spray chamber, where the aerosol is pre-evaporated without solvent removal prior to entering the plasma, was employed for scICPMS analysis of a Se-enriched Saccharomyces cerevisiae (yeast) certified reference material (SELM-1) while monitoring the number of detected cell events. Multivariate optimization of IR-heating temperature, nebulizer gas flow rate, sample uptake rate, and sampling position was conducted. At 150 °C and 5 μL min?1 uptake rate, the IR-heated system achieved a cell transport efficiency of 47 ± 6%, representing a substantial improvement compared with a conventional cyclonic spray chamber (1.1 ± 0.4%) and exceeding that of a commercial single cell introduction system (30 ± 3%). Detection limits of 100–120 ag per cell were obtained for both ??Se and ?2Se. The Se mass per cell determined by scICPMS (65–68 fg cell?1) is consistent with independent estimates derived from certified total Se concentration and bulk digestion measurements, confirming analytical accuracy. Cell lysis occurred at IR-heating temperatures above 220 °C, emphasizing the necessity of optimization using cell-based matrices. Overall, this study demonstrates that controlled IR-heated sample introduction significantly enhances transport efficiency and enables reliable Se quantification in cells without requiring independent transport efficiency calibration.

Abstract:Olivine is a key mineral of mafic-ultramafic and metamorphic rocks. Oxygen isotopic composition of olivine has been widely used to decipher mantle processes, igneous differentiation, and fluid-rock interaction in metamorphic systems. Accurate in situ oxygen isotopic analysis of olivine by secondary ion mass spectrometry (SIMS) requires matrix-matched reference materials to correct instrumental mass fractionation and monitor the stability of instrument. In this study, we report two natural olivine reference materials, AOL (Fo: 91-97) and POL (Fo: 94-97), for in situ oxygen isotopic analysis. These samples exhibit homogeneous oxygen isotopic compositions, with a two-standard deviation of 0.33‰ (N = 105) and 0.37‰ (N = 105), respectively. The recommended δ1?O values, determined by laser fluorination isotope ratio mass spectrometry, are 5.52 ± 0.25‰ for AOL and 5.64 ± 0.13‰ for POL (all ± 2SD, N = 5). Combined with previously reported olivine standards, our results confirm that no significant matrix effects were observed within the forsterite (Fo) content range of Fo?? to Fo??, supporting the wide use of AOL and POL as reference materials for high?precision oxygen isotopic microanalysis.

Abstract:A laboratory-assembled laser-induced breakdown spectroscopy instrument consisting of a compact low-power diode-pumped solid-state laser and a palm-sized low-resolution non-gated spectrometer was evaluated for the quantification of lithium in lithium-bearing ore. Five ore materials containing 0.468 – 2.67 wt.% lithium were analyzed. Three Li I emission peaks at 610, 670, and 812 nm were used after total-intensity normalization. The total-intensity normalization produced a modest improvement in intra-pellet precision but a much larger improvement in calibration accuracy by effectively reducing inter-pellet variation. All three peaks yielded good univariate linear calibration. Among the unconstrained single-peak models, the 670 nm peak showed the lowest prediction error, whereas the 812 nm peak became the best univariate variable when a zero-intercept model was applied, owing to its near-ideal sensitivity and minimal self-absorption. Multilinear regression showed that the combination of the 610 and 812 nm peaks gave the best prediction performance in leave-one-ore-out cross-validation, outperforming all univariate models. In contrast, the use of all three variables did not improve the model further because of strong multicollinearity among the Li peak intensities. These results demonstrate that reliable lithium quantification can be achieved with a low-cost LIBS instrument and that careful selection of a small number of physically meaningful and complementary spectral variables is more important than simply increasing model complexity.

Abstract:In this study, a robust analytical method based on high performance liquid chromatography coupled to inductively coupled plasma - tandem mass spectrometry (HPLC-ICP-MS/MS) was developed and validated for the simultaneous determination of ethylene thiourea (ETU) and propylene thiourea (PTU) in fruits and sulfur-rich vegetables such as plums, apricots, cherries broccoli and Brussels sprouts. Sample preparation was based on a Quick Polar Pesticides (QuPPe) extraction using methanol, followed by an anion-exchange solid-phase extraction (SPE) cleanup to efficiently remove sulfur-containing matrix interferences released during homogenization. Method validation was carried out according to the accuracy profile approach (NF V03-110) across five levels (10-400 μg L?1) for each of the matrices mentioned above. The method showed satisfactory trueness, repeatability, and intermediate precision for both analytes, with limits of quantification of 10 μg L?1 for both ETU and PTU in all matrices. The proposed method demonstrates strong robustness and versatility for the determination of ETU and PTU in challenging sulfur-rich plant matrices and provides a promising ICP-MS/MS-based alternative for the quantification of sulfur-containing organic contaminants in food.

Abstract:Clinopyroxene is a major reservoir for Sr and rare earth elements (REE) in the lithospheric mantle and exerts long-term control on mantle Sr isotopic compositions. High-precision in situ Sr isotopic analysis of clinopyroxene by LA-MC-ICPMS requires matrix-matched reference materials with high Sr contents. However, suitable clinopyroxene reference materials remain scarce, limiting the wider application of this technique. Furthermore, the potential effects of non-matrix-matched calibration on data accuracy have been rarely evaluated. In this study, we present a comprehensive characterization of a potential new high-Sr clinopyroxene reference material, ZYC01, using multiple analytical techniques. ZYC01 exhibits excellent homogeneity in Sr isotopes. It has the highest Sr content (~2000 μg g?1) among all currently reported clinopyroxene reference materials, along with extremely low Rb concentrations. TIMS analyses yield a mean 87Sr/86Sr ratio of 0.705946 ± 0.000006 (2s, MSWD = 0.4; n = 8), while LA-MC-ICPMS analyses give a mean of 0.705956 ± 0.000080 (2s, MSWD = 1.1; n = 308), confirming its suitability as a Sr isotope reference material. Systematic comparison of matrix-matched versus non-matrix-matched calibration for ZYC01 clinopyroxene reveals that synthetic glasses (BCR-2G, BHVO-2G) produce systematic offsets exceeding 0.0004 relative to the TIMS value, while apatite calibration yields a ~0.00006 bias. In contrast, matrix-matched calibration using clinopyroxene YY09-47 gives results in excellent agreement with TIMS. These findings confirm that accurate in situ Sr isotopic analysis of clinopyroxene necessitates rigorous matrix matching. ZYC01 represents a valuable addition to the limited suite of high-Sr clinopyroxene reference materials and will facilitate wider application of in situ Sr isotopic analysis in mantle geochemistry.

Abstract:A digestion-free graphite furnace atomic absorption spectrometry (GFAAS) method was developed for the simultaneous determination of total As and Se in fruit juices using a transversely heated graphite atomizer (THGA) with end-capped pyrolytic graphite tubes fitted with integrated graphite platforms (IGPs). For the analysis, 5 μL of oxidizing reagent (10% (v/v) HNO3 and 60% (v/v) H2O2) with 4 μL of 5 g/L Pd and 5 μL of 0.5 g/L Mg chemical modifier (both applied as nitrates) was directly injected onto the preheated IGP of the THGA (70 oC) along with 5 μL of juice sample. Optimum pyrolysis and atomization temperatures were 1300°C and 2100°C, respectively. Sensitivity of the method, expressed as the characteristic mass, was 22 pg As and 36 pg Se, in quite good agreement with model calculations (19 pg As and 27 pg Se). LODs were 2.1 μg/L (As) and 2.5 μg/L (Se), well below the European Food Safety Authority (EFSA) limits (20 μg/L). The calibration curves of both As and Se were linear up to 150 μg/L. Method validation with sixteen spiked juice samples yielded average recoveries of 93% for both As and Se. The As and Se contents of all juice samples (apple, grape, orange, peach, and mixed fruit) were below the LOD. A conservative dietary exposure assessment using upper-bound assumptions indicated negligible health risk for both elements. The method provides a rapid, green, and reliable approach for routine screening of As and Se in fruit juices.

Abstract:This study presents the development and application of a low-voltage portable atmospheric pressure discharge plasma (LV-PAPD) system coupled with optical emission spectroscopy (OES) for rapid classification of copper alloys. The proposed LV-PAPD source operates at atmospheric pressure and low driving voltage, enabling compact and low-voltage operation without the need for vacuum systems or complex gas handling. Characteristic neutral and ionic emission lines from a wide range of elements were clearly observed, confirming sufficient excitation capability under low-voltage conditions. When applied to Cu-based alloys, dominant Cu emission signals together with dopant-related emissions were identified. Using the regression method, the limits of quantification (LOQs) for Cu and Zn in these alloys were estimated to be approximately 59 wt.% and 23 wt.%, respectively. In addition, machine learning (ML) approaches substantially improve classification performance. Support vector machine (SVM) models achieved classification accuracies of up to 98%, while feature importance analysis from the random forest (RF) model reveals that both strong host-element emissions and weak dopant-related signals contribute significantly to alloy discrimination. The successful differentiation of copper alloys confirms the LV-PAPD-OES system's capability as a portable screening tool for rapid classification of copper alloys.

Abstract:Fluorine determination techniques using inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS), which depend on BaF? detection, are severely constrained in foods with high sulfate content because of the precipitation of barium sulfate. For this purpose, a chloride-enhanced SrF? method was developed using ICP-MS/MS and ammonia as the reaction gas. The signal response of SrF? was increased by up to ~3-fold relative to that in water as the solvent under controlled standard conditions by adding chloride as 4% HCl, which was mechanistically related to the formation of the SrCl+ intermediate. The water-related interferences were lowered by 80% using the Peltier cooling system to keep the spray chamber at ?2 °C. The method showed a linear range of 1?20 mg L?1, an analytical sensitivity of 2.6×103 CPS/mg L?1, and a method detection limit of 4.5×10?3 mg L?1 for fluorine. It demonstrated improved resistance to elevated sulfate concentrations, overcoming one of its main limitations of BaF?-based methods. Analysis of quality control samples and certified reference materials for validation demonstrated good agreement with certified values, while spike recoveries in real food samples ranged from 94.2% to 99.8%.

Abstract:Feature engineering is a critical step in addressing the “curse of dimensionality” and high noise levels inherent in laser-induced breakdown spectroscopy (LIBS) data to enable rapid and accurate classification. However, for complex matrices like uranium (U) slag, individual feature selection methods often struggle to capture the full spectrum of discriminative information, leading to suboptimal model robustness. To address this, a weighted feature fusion (WFF) strategy is proposed for the first time to achieve high-precision classification of U slag. This strategy generates a comprehensive importance metric by performing a weighted linear fusion of normalized scores derived from random forest (RF), least absolute shrinkage and selection operator (LASSO), and mutual information (MI). The influence of diverse weight configurations on support vector machine (SVM), linear discriminant analysis (LDA), and k-nearest neighbors (KNN) models was systematically investigated using LIBS spectra from 23 U slag samples. The results demonstrate that the WFF strategy effectively reconciles the complementary strengths of the baseline methods—leveraging the dominant discriminative power of RF, the sparse linear features of LASSO, and the nonlinear associations from MI. Under the optimal weight configuration (RF: LASSO: MI = 0.5: 0.2: 0.3), the LDA model achieved a peak F1-score of 97.09%, significantly outperforming the best single-method approach (RF-LDA, 94.15%). The proposed strategy exhibits superior generalization and successfully mitigates the adaptation limitations typically observed when specific models are paired with individual selection methods. This study provides a novel, flexible, and interpretable feature engineering solution, offering critical methodological support for the field-deployable monitoring and resource utilization of nuclear-related solid waste.

Abstract:Long-term online monitoring of metals in surface water is essential to protect water resources. Herein, a novel, integrated analytical system encompassing an automatic sample preparation system and solution cathode glow discharge-optical emission spectroscopy (SCGD-OES) for continuous and real-time detection of metals in rivers is presented. A piston pump integrated with a switching valve in the SCGD-OES system enables on-site preparation of water samples and controlled injection of a standard solution with a gradient concentration or environmental samples directly into the SCGD unit. Corresponding hardware and software platforms were developed to support automated operation. Under laboratory conditions, the achieved limits of detection (LODs) for typical metal ions, e.g., Na, K, Ca, and Mg, are comparable to those of conventional SCGD setups. The evaluation of the SCGD system using certified reference materials (CRMs) for water samples demonstrated satisfactory performance for elemental quantitative analysis, with relative errors of 4.1%, 1.9%, 4.0% and 4.5% for the four elements Na, K, Ca and Mg respectively. Furthermore, a seven-day field deployment of the SCGD system at a riverine site confirmed its accuracy and stability, with a relative error of less than 5.7% relative to reference ICP-OES measurements. These results validate the ability of the SCGD system to provide reliable and continuous online monitoring of metals in surface water.

Abstract:Remote quantitative laser-induced breakdown spectroscopy (LIBS) of nuclear fuel materials is a challenging task due to unstable laser delivery and limited plasma emission collection stability. Establishing robust fiber-optic LIBS (FO-LIBS) systems with optimal operational stability is demanding. This study develops a high-throughput FO-LIBS system for quantitative analysis of CeO?-based surrogate nuclear fuel. It incorporates a 10 m, 1 mm core multimode silica delivery fiber, a compact flat-top focusing probe, and a six-channel off-axis emission collection module with a broadband (180–900 nm) detection system. Beam profiling demonstrated that the incident Gaussian beam was transformed into a homogenized flat-top profile after fiber transmission, resulting in improved plasma stability and repeatability. Over 100 consecutive shots, the system achieved a transmission efficiency of approximately 54% with pulse energy variations of less than 2%. The full-spectrum had a relative standard deviation (RSD) of less than 5%. Internal standard normalization using Ce II emission lines produced highly linear calibration curves for La I and Nd II transitions (R2 > 0.99). These findings indicate that the developed FO-LIBS system displayed stable and reproducible quantitative performance, while its detachable probe configuration provides potential flexibility for remote analysis across multiple hot cells in radiation constrained environments.

Abstract:The elemental composition of medicinal materials (MMs) is directly linked to their therapeutic efficacy and clinical safety, making the development of accurate, efficient, and green analytical strategies of elements critically important. This review systematically evaluates recent methodological advancements in elemental analysis (covering both essential elements and toxic heavy metals) in MMs. Firstly, it highlights innovations in green sample pretreatment technologies, including efficient digestion or extraction techniques. Secondly, it comprehensively compares the performance and application scenarios of various analytical techniques, each offering distinct advantages in sensitivity, multi-element analysis capability, and on-site applicability. Subsequently, the review examined the potential influence of elements on the pharmacological activity of MMs and the migration patterns of various elements in the “soil-medicinal plant” system. Finally, it systematically elaborates on precise health risk assessment models, emphasizing the necessity of shifting from total content analysis to a risk-oriented evaluation paradigm. This review aims to provide a comprehensive reference for the development of green analytical methods, risk assessment, as well as quality and safety control of MMs.