Preparation of REE-doped NaY(WO4)2 single crystals for quantitative determination of rare earth elements in REE:NaY(WO4)2 laser crystals by LA-ICP-MS

Preparation of REE-doped CaF2 single crystals for accurate determination of REE concentrations in CaF2 crystals via UV-LA-ICP-MS

Accurate determination of rare earth element (REE) concentrations in CaF2 crystals using UV-LA-ICP-MS is important but challenging due to the lack of matrix-matched reference materials. In this study, a REE-doped CaF2 single crystal (CaF2-05), prepared via the Bridgman-Stockbarger technique, was systematically characterized to assess its optical properties, homogeneity, and stability. Analyses using portable laser irradiation, UV-vis spectroscopy, back scatter electron (BSE) imaging, and cathodoluminescence (CL) demonstrated that the crystal possesses high optical quality and exhibits distinct optical adsorption properties compared to the silicate reference material NIST SRM 610. The within-unit variation (Sr) ranged from 3.82 % to 9.86 %, the between-unit Sr varied from 3.94 % to 7.85 %, and the mean square weighted deviation (MSWD) was close to 1, indicating minimal chemical heterogeneity. These results are comparable to those of certified reference materials and other home-made calibration standards. Femtosecond LA-ICP-MS mapping further confirmed the homogeneous distribution of REEs within the CaF2 crystal. Stability tests conducted from April to November 2024 demonstrated the crystal's good long-term stability. The method's accuracy was validated by calibrating REE concentrations in another CaF2 single crystal (CaF2-005), with measured REE concentrations closely matching reference values. The relative deviations (Dr) primarily ranged from -10.10 % to 12.79 %, which is significantly more accurate than the non-matrix-matched calibration using NIST SRM 610. These findings demonstrate that this method provides reliable accuracy and holds promise for application in the accurate determination of REE concentrations in CaF2-matrix samples, such as CaF2 luminescent materials and natural fluorite ores.

Preparation of matrix-matched calibration standards for accurate determination of elemental concentrations in uric acid stones by LA-ICP-MS

Accurate determination of elemental concentrations in uric acid (UA) stones is crucial for understanding their formation process. However, the lack of matrix-matched calibration standards has limited the application of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) in this field. This study addresses this limitation by preparing a synthetic UA precipitate (UA-1) doped with 17 elements using a recrystallization method. Reference concentrations of these elements were measured using pneumatic nebulization-ICP-MS (PN-ICP-MS) for calibration purposes. The synthetic standard was characterized through 30 random spot analyses, demonstrating a homogeneity of approximately 5%. Using this synthetic standard, a reliable analytical method was developed, achieving limits of detection (LODs) ranging from 0 to 0.42 μg g-1. The method's accuracy, with relative deviations between -8.33% and 0 and correlation coefficients (R2) greater than 0.99, confirms its reliability. Additionally, elemental distribution differences observed across various zones in a real UA stone suggest that this method offers a promising approach for the precise analysis of elemental concentrations in UA stones.

A green and facile direct ink writing technique for preparation calibration standards in laser ablation inductively coupled plasma mass spectrometry analysis

BACKGROUND

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a powerful tool for microanalysis of solid materials. Nevertheless, one limitation of the method is the lack of well-characterized homogeneous reference materials (RMs), such as BaF2 crystal and BaCO3 ceramics samples, making direct quantification difficult. This work presents a novel Direct Ink Writing (DIW) method to produce RMs for microanalysis. The Mg, Cr, Fe, Co, Ni, Cu, Y, Mo, Pr, Gd, Dy, Ho, Er, Tm, Yb, and Lu solutions were gravimetrically doped into BaCO3 by mixing with the dispersant and then cured with DIW techniques. (94) RESULTS: BaCO3 powder was combined with a dopant analyte to produce a printable slurry, aided by the use of a dispersant and cellulose. The resulting mixture was then printed using DIW equipment. The retention rates of the doped elements were investigated by internal and external standard method, and the results showed that they were completely dispersed in the solid material. After further optimization, it was found that there was no significant heterogeneity among the printed samples. LA-ICP-MS was used to analyze printed samples, to evaluate micro-scale homogeneity. The mass concentration of the doped element was determined by ICP-MS, verify its move closer to nominal value. Compared with the traditional reference materials preparation methods, the DIW technology greatly increased the sample homogeneity and the accuracy of the desired concentration. (132) SIGNIFICANCE: As far as we know, there are few reports on the application of DIW method to prepare calibration standards. In brief, it is proved that the proposed method of preparing calibration standard by DIW technique to quantify analytes is valid and robust. This procedure provides great potential for LA-ICP-MS in-situ analysis in the field of well-prepared products, such as ceramic and crystal samples.(63).

Multi-element imaging of urinary stones by LA-ICP-MS with a homogeneous co-precipitation CaC2O4-matrix calibration standard

Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) studies on trace element concentration and their spatial distribution in CaC₂O₄-matrix urinary stones are important but powerfully rely on matrix-matched external calibration. In this work, CaC₂O₄ precipitate CaOx-1 which was doped with Mg, Cr, Mn, Fe, Co, Cu, Zn, and Sr was prepared by the homogeneous co-precipitation method. It had a homogeneous distribution of major (RSD of 0.46%) and trace elements (RSD of 1.83-6.92%) due to the negligible concentration difference compared with that prepared by the heterogeneous co-precipitation method. Based on this, an analytical method for quantitative determination of elemental concentration in CaC₂O₄-matrix samples was established using CaOx-1 as a calibration standard, and the accuracy of this method was assessed by calibrating the elemental concentration in another synthetic CaC₂O₄ precipitate CaOx-2 with relative deviation (D_r) from - 11.43% (Mn) to 9.76% (Mg). Finally, a methodology for quantitative imaging of Mg, Cr, Mn, Fe, Co, Cu, Zn, and Sr in urinary stones via LA-ICP-MS was developed. From the elemental distributional maps, an annular texture can be found for Mg, Cu, Zn, and Sr, which corresponds to the annular white and brown texture in the real urinary stone. A homogeneous distribution of Fe and low concentrations of Cr and Co were found throughout the stone, while Mn was highly concentrated in the margin of the stone. All these results demonstrate that quantitative distribution patterns of Mg, Cr, Mn, Fe, Co, Cu, Zn, and Sr can be obtained by LA-ICP-MS using CaOx-1 as a calibration standard, which can provide potential evidence for urological and other medical studies.