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Single shot laser ablation MC-ICP-MS for depth profile analysis of U isotopes in UO <sub/>2</sub> single crystals
摘要： An analytical procedure for determining the n(235U)/n(238U) amount ratio in consecutive layers of UO2 single crystals was developed and validated. A 25 mm circular shaped laser beam with a fluence of only 0.24 J cm?2 was employed for depth profiling 235U and 238U in UO2 single crystals with U isotopes being detected via MC-ICP-MS. The time-resolved 235U and 238U MC-ICP-MS signals obtained from individual laser shots were processed automatically using software specifically developed for this purpose. Downhole fractionation of the n(235U)/n(238U) amount ratio was excluded by shooting 80 laser pulses on a reference UO2 single crystal of known composition, revealing no measurable change in its U isotopic ratio during depth profiling. A linear relationship between the number of laser shots and the average depth of the laser ablation craters was established using confocal laser scanning profilometry. The ns-laser ablation system produced conical craters whose diameters were shown to increase with the number of laser pulses. The shape and roughness of the craters were studied as a function of both the number of pulses and focusing conditions. Using a dual beam focused ion beam (FIB), high resolution scanning electron microscopy (SEM) micrographs revealed the formation of rectangular “tiles” on the reference UO2 single crystal after as little as five laser shots. The ordered, rectangular structure disappeared progressively with increasing number of laser pulses, while simultaneously a sub-micrometric porosity developed. The depth profiling capabilities of the laser ablation system were applied to two UO2 single crystals produced under different experimental conditions involving solid state isotopic mixing of 235U and 238U in order to characterise U self-diffusion in UO2+x. Both UO2 single crystals featured a n(235U)/n(238U) ratio gradient, containing enriched U at the surface and depleted U in the bulk.
关键词： MC-ICP-MS,UO2 single crystals,depth profile analysis,laser ablation,U isotopes
更新于2025-09-11 14:15:04
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A combined chemical imaging approach using (MC) LA-ICP-MS and NIR-HSI to evaluate the diagenetic status of bone material for Sr isotope analysis
摘要： This paper presents a combination of elemental and isotopic spatial distribution imaging with near-infrared hyperspectral imaging (NIR-HSI) to evaluate the diagenetic status of skeletal remains. The aim is to assess how areas with biogenic n(87Sr)/n(86Sr) isotope-amount ratios may be identified in bone material, an important recorder complementary to teeth. Elemental (C, P, Ca, Sr) and isotopic (n(87Sr)/n(86Sr)) imaging were accomplished via laser ablation (LA) coupled in a split stream to a quadrupole inductively coupled plasma mass spectrometer (ICP-QMS) and a multicollector inductively coupled plasma mass spectrometer (MC ICP-MS) (abbreviation for the combined method LASS ICP-QMS/MC ICP-MS). Biogenic areas on the bone cross section, which remained unaltered by diagenetic processes, were localized using chemical indicators (I(C)/I(Ca) and I(C) × 10/I(P) intensity ratios) and NIR-HSI at a wavelength of 1410 nm to identify preserved collagen. The n(87Sr)/n(86Sr) isotope signature analyzed in these areas was in agreement with the biogenic bulk signal revealed by solubility profiling used as an independent method for validation. Elevated C intensities in the outer rim of the bone, caused by either precipitated secondary minerals or adsorbed humic materials, could be identified as indication for diagenetic alteration. These areas also show a different n(87Sr)/n(86Sr) isotopic composition. Therefore, the combination of NIR-HSI and LASS ICP-QMS/MC ICP-MS allows for the determination of preserved biogenic n(87Sr)/n(86Sr) isotope-amount ratios, if the original biogenic material has not been entirely replaced by diagenetic material.
关键词： LASS ICP-QMS/MC ICP-MS,Diagenesis,Human bone remains,Near-infrared hyperspectral imaging
更新于2025-09-10 09:29:36
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Measuring heavy metal content in bone using portable X-ray fluorescence
摘要： The ability of inorganic-based analytical chemistry techniques to quantify trace amounts of heavy metals in skeletal remains has been integral for understanding health and social status in human populations. Low detection limits and the sensitivity of inductively coupled plasma-mass spectrometry (ICP-MS) and other techniques to most elements on the periodic table are ideally suited for the quantification of lead (Pb) and other heavy metals in bone. However, the time required for sample preparation and analysis, expense, destructive analytical process, and availability of instrumentation often limit researchers’ ability to utilise these techniques for archaeological applications. This paper explores the use of portable X-ray fluorescence (XRF) instrumentation for heavy metal analysis of bone as an alternative to more traditional analytical techniques. XRF has been shown to be an extremely useful tool for archaeologists seeking to conduct quantitative analyses of cultural materials such as obsidian and metals. However, little research has been undertaken to assess the usefulness of portable XRF for measuring heavy metals found in low concentrations in archaeological bone. This paper compares data derived from ICP-MS and portable XRF analyses of bone. Results demonstrate that XRF analyses of bone are problematic due to diagenesis and variability of Pb content in bone.
关键词： LA-ICP-MS,lead,human bone,portable XRF
更新于2025-09-10 09:29:36
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Nano ZrO2 Synthesis by Extraction of Zr(IV) from ZrO(NO3)2 by PC88A, and Determination of Extraction Impurities by ICP-MS
摘要： High purity Zirconium (Zr) materials are essential in many components of nuclear reactors, especially fuel cladding tubes. Due to the matrix in?uence, determination of impurities in the Zr materials requires separation from the Zr matrix. Among extraction methods, solvent extraction is common and suitable for large-scale production. In this study, extraction capability of Zr(IV) by 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester (PC88A) was examined by FT-IR and UV of ZrO(NO3)2 salt, PC88A-toluene solvent, and Zr-PC88A-toluene complex. ZrO2 (obtained from Institute for Technology of Radioactive and Rare Elements—ITRRE), after being separated from the Zr matrix, was determined for impurities using internal standard (indium, In) by 50% of PC88A dissolved in toluene. Separation of impurities from the Zr matrix underwent two stages. First, one cycle of extraction of the Zr matrix and impurities in 3 M HNO3 using 50% PC88A/toluene was conducted. Second, impurities were scrubbed by 4 M HNO3 in two cycles. Results revealed that approximately 74% of Zr(IV) was separated to the organic phase and 26% remained in the aqueous phase. Determination of impurities after separation from the Zr matrix by ICP-MS using internal standard in revealed that the recovery of impurities achieved 95–100%. With the mentioned amount of Zr, the effect of the Zr matrix on the determination of elements by ICP-MS is negligible. Levels of impurities have relative standard deviations (RSD) of less than 6.9% and recovery of 88.6–98.8%. Therefore, the determination of impurities has high reliability and accuracy. The back-extraction of Zr(IV) in organic phase by 1 M H2SO4 has stripped about 99.5% of the Zr matrix back to the aqueous phase. Following this, NH3 was added to the solution containing Zr after back-extraction to form Zr(OH)4 which was then desiccated to produce ZrO2. X-ray Diffraction (XRD), Scanning and Transmission Electron Microscopy (SEM and TEM) images showed that the new ZrO2 product has spherical nanostructure with diameters of less than 25 nm, which is suitable for applications for the treatment of colorants, metal ions in wastewater sources and manufacture of anti-corrosion steel. In addition, the energy dispersive X-ray (EDX) of the new ZrO2 product showed that it has high purity.
关键词： extraction,nano ZrO2,impurities,PC88A,ICP-MS,high purity Zr
更新于2025-09-09 09:28:46