Spectrochimica Acta Part B: Atomic Spectroscopy最新文献

Long-lived trans‑uranium nuclides such as ²³⁷Np, may reside in the environment for long period and result in ecological impact and human health threat. Accurate measurement of ²³⁷Np in the environment is important for the risk assessment and ecological evaluation. However, the spectral peak tailing and polyatomic ions interference greatly limit the measurement of ²³⁷Np with triple quadrupole ICP-MS (ICP-MS/MS), which have been successfully used for analysis of ultra-trace level ^239,240Pu and ²⁴¹Am. The novel methods for ²³⁷Np measurement with ICP-MS/MS in both on-mass and mass-shift modes were examined in this paper. When helium was used as the collision gas for the ICP-MS/MS measurement with on-mass mode, the interference contribution to the counts for ²³⁷Np (at m/z 237) as low as 4 × 10⁻⁸ was observed only from Hg, while no measurable interference from Tl and Pb was observed. Moreover, when the mass-shift mode is employed with O₂/He and He as the collision/reaction gas, the interference contributions from Hg, Tl and Pb were all negligible. The detection limit of ²³⁷Np was reduced to 0.014 fg/g and 0.019 fg/g for on-mass and mass-shift mode, respectively. The novel methods were demonstrated to enable accurate determination of 1.0 fg/g level ²³⁷Np in the emulated sample solutions with a ²³⁷Np/²³⁸U atomic ratio as low as 10⁻⁹. Combined with appropriate chemical separation procedure, the developed methods were verified with certified reference materials and soil samples.

Accurate detection and quantification of hydrogen isotopes in solid materials are vital for diverse applications, including fusion energy, hydrogen storage, and tritium production. Laser-induced breakdown spectroscopy (LIBS) is a well-established, rapid, standoff method for this purpose, but it faces challenges related to the analytical merits required for isotopic analyses. In this study, we enhance the analytical and detection capabilities of traditional single-pulse LIBS by implementing an orthogonal double pulsing approach, focusing on the analysis of a range of ${}^{2}H$ concentrations in Zircaloy-4 substrates (acting as a proxy for ${}^{3}H$). The double-pulse experiments employed an orthogonal re-heating configuration with two nanosecond Nd:YAG lasers. We systematically evaluated critical parameters affecting the signal intensity in double-pulse LIBS, including interpulse delay, ambient gas pressure, and heating laser energy. Our results demonstrate that employing an orthogonal double-pulse scheme significantly enhances ${}^2{H}_{\alpha }$ emission while minimizing line broadening and self-absorption, ultimately improving the technique's analytical capabilities.

In recent years, the increasing demand for extensive strontium (Sr) datasets across various scientific fields has prompted the development of fast, precise, and reliable protocols. These protocols aim to achieve high sample-throughput without compromising data quality. A novel method termed the zirconium (Zr) doped sample-standard bracketing (SSB) has been recently introduced for isotope measurements using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). This method allows for simultaneous acquisition of ⁸⁷Sr/⁸⁶Sr and δ⁸⁸Sr data without the need for sample spiking. However, the reliability of this method in handling large datasets and ensuring long-term reproducibility requires additional documentation. A comprehensive examination of the reliability of Sr isotope data over two years involves the implementation of systematic tests on reference materials from the National Institute of standards and technology (NIST) with the standard reference material (SRM) numbers: 1400, 1515, 987, 2910b, 1486, as well as a Hawaiian volcano observatory basalt (BHVO-1). The results of this study lead to the definition of a set of quality control parameters. The developed protocol applies various controls to ensure precise matching of Sr and Zr concentrations for both the samples and the bracketing standard (NIST SRM 987), along with the identification of instrumental biases. The outlined quality control ensures the reproducibility of the results (⁸⁷Sr/⁸⁶Sr = 0.710247 ± 0.000026, 2SD, n = 557; and δ⁸⁸Sr = 0.001 ± 0.053 ‰, 2SD, n = 537 for NIST SRM 987), proving invaluable for archaeological, geological, and ecological studies requiring the fast acquisition of extensive datasets (n > 100) to create isotopic baselines.

Understanding the distribution and concentration of Rare Earth Elements (REE) within various minerals and ores is crucial in mineralogy and geology for comprehending the micro-scale processes that contribute to the formation of REE-bearing minerals. Laser Induced Breakdown Spectroscopy elemental imaging emerges as a valuable tool due to its spatial resolution (15 μm) and ability for blind and rapid identification of elements within thin rock sections. Geological samples from the metamorphic core of the Zagros orogen (Iran) prepared as thin rock sections have been analyzed by LIBS imaging. Mineralogical phases have been determined from LIBS images of major elements. We first found that the distribution of Yttrium and REEs varies depending on the metamorphic stage. Then, while garnets may exhibit zoning in Mn, we observed that not all of them incorporate Yttrium. Finally, we demonstrated that REEs carriers include bastnaesite (Y Ce La F) and xenotime-like minerals primarily composed of Y with varying amounts of Yb, Gd, and Nd. We also demonstrated that the REEs minerals can exhibit either millimetric size when embedded within andalusite phases, or micrometric size when randomly scattered throughout the matrix. And we have also observed that some samples feature abundant Y-enriched Zircon phases. This study demonstrates that μLIBS imaging enables drawing a comprehensive picture of geological samples down to the micrometric scale. It has become a key technique in this field, providing access to the mineralogy of REE minerals, which is paramount for optimizing the final exploitation process compared to other analytical techniques.

Analysis of elements in liquid samples via X-ray fluorescence (XRF) faces challenges due to diverse matrix effects. To address this, the use of glass fiber filters (GFFs) as effective substrates for XRF analysis was explored. The matrix compositions of various commercial GFFs were comprehensively analyzed and compared to assess their applicability in liquid analysis. Most GFFs do not contain heavy elements, exhibit highly consistent filter weights, and have matrix element contents with relative standard deviations (RSDs) below 3%, which are ideal for detecting heavy elements. GFFs were also demonstrated to have superior analytical sensitivity compared to alternative filters. Optimal analytical performance can be achieved by utilizing a 30 mm sample holder, dripping 50 μL of the sample on the uniformly pressed GFFs, and drying it via infrared heating. Most heavy elements showed wide linear concentration ranges spanning over three orders of magnitudes and limits of detection (LOD) lower than mg/L. The results of standard addition and recoveries in natural lake water were promising. Furthermore, GFFs proved capable of verifying the composition and quality of particulate materials. The used GFFs can also be easily regenerated through acid washing for reuse. Therefore, GFFs are optimal XRF substrates for analyzing liquid samples containing heavy metal ions and materials.

Femtosecond-laser ablation is becoming increasingly popular due to its advantageous characteristics such as reduced fractionation and improved lateral resolution. However, since the emission from the resulting laser-induced plasmas is reduced and relatively short-lived, optical spectroscopy analyses with fs lasers (LIBS) are often carried out with enhancement strategies, such as double-pulse LIBS. For orthogonal double pulse set ups, characterizing the spatio-temporal excitation of the fs-LIP can be useful to fully optimize the scheme. This work aims to characterize the structure of a fs-laser induced plasma in atmospheric pressure, illustrating the general behavior of the plasma plume for different target materials (metals and dielectrics), and further obtain insight about the emission and excitation characteristics of the plume for pure copper and PVC samples. The results show a clear two-component structure of the metallic plumes, composed by a fast-displacing upper component that presents higher excitation and higher ionization degree and a slow, almost static component that remains near the sample surface throughout the complete evolution. On the contrary, PVC presented only one fast-displacing component which was seen not to be homogeneous in terms of excitation. As a general feature, in the present study conditions, all the plasma plumes induced in different samples presented an intensity-dominating fast component, with discrepancies in the presence and relative intensity of the slow component.

Water quality monitoring is an important part of environmental protection, and the ability to qualitatively and quantitatively determine the level of impurities in water is especially important. Laser-induced breakdown spectroscopy (LIBS) has become a promising technique compared with the currently available water quality control methods. LIBS has several advantages, including minimal or no sample pre-treatment, fast and easy operation, and a chemical-free process. This article reviews the studies conducted on LIBS analysis for the detection of heavy metals in water samples. The article describes a historical perspective at the progress of LIBS, the LIBS instrumentation, LIBS procedures without pre-treatment and different pre-treatment methods of aqueous samples for improving the limit of detection (LOD), quantitative analysis of metallic elements in liquids, LIBS signal enhancement methods and data processing, characteristics of plasma generated by laser in water, improving the LIBS sensitivity for the detection of trace heavy metals in aqueous solutions, factors affecting the accuracy of the analysis results, and LIBS spectra after measurements. This review will help readers better understand the LIBS technique for detecting heavy metals in liquids and identify current research requirements for environmental water quality monitoring.

A procedure for the determination of traces of lead and tin by electrothermal atomic absorption spectrometry (ETAAS) after complexation with diethyl dithiophosphate and preconcentration by using a microextraction stage with a magnetic ionic liquid (MIL) supported by ferrite particles is presented. After complexation, the analytes are extracted into the ferrite-supported MIL, the solid particles acting as a carrier to facilitate the separation with a magnet. The analytes are released by treating with acetonitrile and the resulting liquid phase is sampled for the ETAAS measurement. The optimal experimental conditions such as pH, appropriate complexing agent, volumes and doses of all reagents used in the procedure are studied to achieve complete separation of both species. Enrichment factors of 195 and 165 and detection limits of 25 and 72 ng L⁻¹ are obtained for Pb and Sn, respectively. The reliability of the procedure is checked by analyzing six certified reference materials and applied to water samples of different origin, the results being in addition confirmed by standard additions (recoveries 97 ± 7% in all cases).

In this paper we test new approaches for predicting the amount of element oxides in rock samples from the ChemCam instrument suite onboard the NASA Curiosity rover by focusing on $K_{2}O$. Using the expanded dataset compiled by Gasda et al. (2021) with and without the Earth to Mars (E2M and NoE2M) transformation discussed in Clegg et al. (2017) we trained blended submodels using the “double blending” technique and compared these to ensemble methods (Random Forest, ExtraTrees, and Gradient Boosting Regression). We found that ensemble methods performed similar to blended submodels when looking at RMSE-P on the laboratory spectra and provided significant advantages when looking at spectra coming from Mars. For the full model, blended submodels achieved an RMSE-P of 0.62 and 0.60 (E2M and NoE2M respectively) while Gradient Boosting Regression resulted in a slightly improved RMSE-P of 0.59 and 0.60. More importantly, by employing a local RMSE-P estimation technique where model performance is evaluated based on nearby test samples we found that using ensemble methods can lower the quantification limit for $K_{2}O$ from the current value of ≈0.6 wt% to ≈0.08 wt% using Extra Trees and Random Forest. This would allow for a much larger range of $K_{2}O$ values to be quantified on Mars with greater certainty given that most targets seen on Mars tend to have <1 wt% $K_{2}O$. Finally, we used both Mean Decrease in Impurity (MDI) and permutation importance techniques to investigate the wavelengths used by the ensemble methods and found that they correspond to known potassium emission lines. This suggests that ensemble methods can provide an easier to train and improved alternative to blended submodels for predicting potassium compositions from Laser Induced Breakdown Spectroscopy (LIBS) data.