Journal of Analytical Atomic Spectrometry最新文献

Halogen detection, especially in a multielement fashion and with liquid chromatography, is challenging because of the fundamental limitations of ionization in inductively coupled plasma (ICP) mass spectrometry. Post-plasma ionization alleviates these limitations. For Cl detection, plasma-assisted HCl formation followed by chemical ionization using barium-containing reagent ions has been reported, yielding BaCl⁺ and offering simultaneous detection with other halogens (e.g. F detection using BaF⁺). However, the broad reactivity of barium-based ionization also makes it susceptible to interference from other plasma-generated species, increasing the potential for ionization suppression, sensitivity loss, and elevated matrix effects. Here, we report the development of HCl-selective post-plasma ionization reactions to improve ionization robustness and matrix tolerance in Cl detection. We evaluate a series of metal ions (M) with aqueous-phase affinity for chloride to determine their potential to form MCl(NO₃) _n ⁺ (n = 0-1) in the post-ICP region. We show that metal ions follow the order Pb²⁺, Bi³⁺, Cd²⁺ > In³⁺ > Zn²⁺, Fe³⁺ >> Ba²⁺ in terms of propensity of their reagent ions to react with HCl in the presence of interfering plasma products such as HNO₃ and HNO₂. Among the metal ions, Pb²⁺ also offers the highest sensitivity for Cl detection because of efficient reagent ion generation by electrospray ionization. The robustness of PbCl⁺ detection is also tested in P-containing matrices, revealing a 5-fold improvement relative to that with BaCl⁺ and further confirming improved matrix tolerance due to more selective ionization reactions. These studies offer fundamental insights and pave the way towards robust multielement methods for halogen detection in speciation analyses.

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This study investigates a spatial confinement approach utilizing cylindrical cavities to mitigate plasma self-absorption effects in laser-induced breakdown spectroscopy (LIBS)—a critical limitation for quantitative analysis. Experiments systematically evaluate atomic lines (Al I 396.15 nm, Cu I 521.83 nm, and Mg I 517.27 nm) and an ionic line (Mg II 293.65 nm) of the 6061 Al alloy, T2 Cu, and AZ31B Mg alloy. Results demonstrate that confinement reduces self-absorption through three mechanisms: restricting plasma expansion, elevating the electron temperature, and reducing the ground-state particle density. Optimal reduction occurs at a cavity height of h = 12 mm and a radius of r = 8 mm. Specifically, ionic lines (e.g., Mg II 293.65 nm, ionization energy = 8.65 eV) exhibit significantly stronger reduction than atomic lines under identical conditions, which is attributed to their higher ionization energies and narrower spectral widths. This differential response originates from the reduced ground-state particle density and complex transition pathways in ionic species. The technique effectively minimizes spectral line attenuation and broadening, thereby providing physical insights into the confinement-mediated mitigation of self-absorption and offering a potential strategy for improving quantitative LIBS analysis.

Shock layer thermochemistry during atmospheric reentry of spacecraft is strongly influenced by the composition of thermal protection system (TPS) materials. In this study, we implement calibration-free laser-induced breakdown spectroscopy (CF-LIBS) to profile cross-sections of phenolic impregnated carbon ablator (PICA) and room temperature vulcanizing (RTV) silicone from the heatshield of a commercial reentry capsule. CF-LIBS measurements determine that these materials contain alkali and alkaline earth contaminants (e.g., Na, Ca) at levels up to 10 parts-per-million (ppm) and heavier metals like Fe at 10³ ppm. Contaminant concentrations are linked to observed strong atomic radiators identified from in situ shock layer emissions taken during reentry, demonstrating the value of CF-LIBS for interpreting complex shock-layer emission data from reentry spacecraft.

The L X-ray spectrum induced by electron impact upon a solid germanium target was measured with high spectral resolution and analyzed using the POEMA fitting software. Characteristic transition energies, natural linewidths, and relative radiative transition probabilities were determined for the main diagram lines. In addition, a comprehensive identification of satellite decays was achieved, including features previously unreported; the corresponding energy shifts were found to agree with literature values. New satellite structures in the and Lη regions were also observed, with the large linewidths found suggesting contributions from multiple unresolved transitions. The intensity-ratio analysis reveals a significant role of multivacancy states, with the Lβ₁ transition exhibiting an unusually high satellite-to-main intensity ratio close to unity, evidenced by the careful spectral treatment carried out. To accurately reproduce this region, we applied the self-absorbed Voigt profile previously developed for L-emission spectra, which incorporates an energy-dependent absorption term to account for the variation of the absorption coefficient across the neighbouring L₃ edge. This approach successfully reproduces the low-energy asymmetry of the Lβ₁ peak and its effect on the relative intensities of the main and satellite components. The results obtained aim to complete the database available at present for Ge L X-ray parameters, providing methodological advances applicable to the spectroscopic study of other elements.

Quadrupole inductively-coupled-plasma mass-spectrometers (Q-ICP-MS) are used to analyse enormous numbers of isotope ratios, most prominently ²⁰⁶Pb/²³⁸U for age determination. With the advent of reaction-cell equipped tandem Q-ICP-MS (Q-ICP-MS/MS), the scope for isotope ratio determination has grown, especially for β-decay isotope systems (e.g., ⁸⁷Rb/⁸⁷Sr). Reaction of unwanted interfering species (e.g.²⁰⁴Hg on ²⁰⁴Pb) has also increased the feasibility of Pb-isotope ratio measurements by Q-ICP-MS. Unlike in sector-field MS isotope ratio analysis where mass bias is corrected via a known isotope ratio or with calibrated double or triple-spikes, Q-ICP-MS(/MS) analysts generally apply an ‘external correction’ with reference to interleaved calibration standard analyses. Despite this protocol, there remains inaccuracies in derived isotope ratios when compared to reference values which are inadequately explained. The aim of this study was to investigate the origin of the inaccuracy in Q-ICP-MS isotope analysis, which has so far received surprisingly little attention. We assessed whether improved detector dead time correction can achieve more accurate isotope results and explored fractionation effects arising from steering ion beams across complex Q-ICP-MS/MS paths. We investigated detector dead time as a function of Z in both single MS and mass-shifted MS/MS mode. We document how dead time varies over time as detectors and electronic components of the ICP-MS age. We show that session specific dead times yield substantially more accurate isotope ratios for mass shifted Sr isotope ratios than when applying a generic dead time. We also provide recommendations for how to incorporate session-specific dead time analyses into an isotope ratio run. Despite the much-improved quality of dead time and conventional mass bias corrected mass shifted Sr isotope ratios, small (up to 4‰) inaccuracies remain. The inaccuracy is systematic and specific for each session. Therefore, it can be corrected with a small bias correction relative to a CRM analysed throughout the session. The origin of the Sr isotope ratio inaccuracy after dead time and conventional mass bias correction remains speculative. Our exploratory analysis suggests that voltages on lenses tuning and directing the ion beams through the MS/MS may be a source of an additional isotope fractionation process (bias) that cannot be fully corrected with conventional mass bias procedures.

To address the challenge of limited and unstable spectral data from portable laser-induced breakdown spectroscopy (LIBS) devices, this study employed a transfer-learning framework augmented with simulated data. A lightweight one-dimensional convolutional neural network (1D-CNN) was developed, allowing knowledge transfer from high-quality simulated or laboratory spectra to portable-device measurements. Under small-sample and noisy conditions, the transfer-learning approach significantly improved the regression accuracy and stability compared to the performance of the baseline CNN model. Experimental evaluation on multiple elements demonstrated that when simulated data serve as the source domain, the regression performance approaches that achieved using high-precision laboratory spectra and, for certain elements, surpasses that of traditional real-data transfer learning. These results suggest that simulated data-based transfer learning constitutes a viable strategy for enhancing the quantitative analytical performance of portable LIBS systems, particularly under field conditions where high-quality spectral data are difficult to obtain.

Halogens, including fluorine (F) and chlorine (Cl), play essential roles in magmatic, hydrothermal, and ore-forming processes. Determining their geochemical behaviors is challenging due to their low abundance and volatility. Apatite containing halogens serves as an ideal recorder of Earth's and planetary processes. This study presents a quantitative method using molecular emission spectra of calcium fluoride (CaF) and calcium chloride (CaCl) to measure F and Cl concentrations in apatite through femtosecond laser-induced breakdown spectroscopy (fs-LIBS). Reference materials with varying F and Cl levels were employed to optimize conditions and develop calibration curves for F (0.55–3.75 wt%) and Cl (0.45–4.26 wt%), with detection limits of 0.22 wt% and 0.38 wt%, respectively. The calibration curves achieved R² values of 0.995 for F and 0.992 for Cl, with RMSRE of 8% for F and 13% for Cl. Validation using natural apatite samples confirmed accuracy within ± 0.10 wt% compared to EPMA data. The fs-LIBS technique offers potential for accurate and precise measurement of F and Cl in minerals when reference materials are available.

Sodium is a preferred coolant in Generation IV nuclear reactors due to its excellent heat transfer and nuclear properties. However, decreased cooling efficiency, material corrosion and blockages can be caused by excessive amounts of impurities in the sodium. Conventional detection methods are unable to realize rapid, in situ, sensitive and accurate online sodium impurity monitoring owing to factors such as equipment size, service life and detection time. In this study, a laser-induced breakdown spectroscopy device with a gas protection component was proposed. This design not only prevents sodium aerosols or liquid sodium splashing from contaminating the optical lens, but also enables sensitive analysis of Fe and O in sodium, with limits of detection of 0.68 µg g⁻¹ and 0.11 µg g⁻¹ and RSDs of 7% and 4%, respectively. The results demonstrated that this method has potential application prospects in the nuclear industry and could provide a guarantee for the safe operation of sodium-cooled fast reactors.