Speciation Techniques Research Articles

Determination of toxicological relevant arsenic species in urine by hydride generation microwave-induced plasma optical emission spectrometry

An analytical method for the determination of toxicological relevant species of arsenic in urine was developed and validated using hydride generation microwave-induced emission spectrometry (HG-MP-AES). This strategy can be used as an alternative to HG-HPLC-ICP-MS considered as a reference technique for arsenic speciation. This procedure is notably less expensive than other techniques and sample preparation and requires only a few steps.•Hydride generation with MP-AES detection has proven to be an effective technique for measuring arsenic metabolites in urine, which is relevant for occupational monitoring and health risk assessment purposes.•This method offers simplicity and cost-effectiveness, serving as an alternative to classical analytical procedures typically used for arsenic analysis in urine.•The methodology has been successfully applied for the purpose of workers' health surveillance.

The comprehensive strategy in the human health risk assessment of total chromium impurities in cough syrups with Marshmallow Root (Althaea officinalis) available in Polish pharmacies: regulatory aspects and special emphasis on Cr(VI) mode of action

Chromium, which can currently only be considered pharmacologically active and not an essential element, is a very intriguing elemental impurity in final pharmaceutical products, especially traditional herbal medicinal products. This kind of traditional herbal medicinal product with Marshmallow root (Althaea officinalis L., radix) registered in the EU is widely used among the European population. The aim of this article is to propose a double regulatory strategy in assessing the human health risk of total chromium impurities in cough syrups with Marshmallow Root (Althaea officinalis) available in Polish pharmacies. We applied the strategy based on the requirements of the ICH Q3D (R1) guideline for the assessment of Cr impurities in final traditional herbal medicinal products with Marshmallow Root registered in the EU. Furthermore, we applied the strategy based on the concept of margin of exposure (MoE) considering Cr(VI) genotoxicity mode of action (MOA) and based on BMD10 for Cr(VI) as a point of departure (PoD). The total Cr content was in the range: 1.12–9.61 µg/L (in comparison with the ICH Q3D R1 guidelines: 1100 µg/g). Total Cr levels in a single dose were relatively high compared to raw results, but were not a threat to patients. Comparison of estimated results with oral PDE value for Cr in final drugs suggested by the ICH Q3D R1 guideline (10,700 µg/day) show that all the products analyzed were below this value (the highest result was 278.40 ng/day). Despite conservative assumptions, the MoE values obtained for Cr in daily dose for each Marshmallow Root cough syrup were above 10,000; therefore, exposure to Cr would not cause a health risk for specific population groups (children and adults). It can be summarized that each of the phytopharmaceuticals analysed with Marshmallow root available in Polish pharmacies does not represent a health hazard to patients. We confirm the safety of Cr impurities by applying a double regulatory strategy without the application of an expansive and demanding HPLC-ICP-MS technique for Cr speciation.

WD‐XRF technique for speciation of iron and quantification of its oxidation states in geological samples using L‐series of iron X‐ray spectrum

AbstractWavelength dispersive X‐ray fluorescence (WD‐XRF) spectrometry is a fast and widely used technique for elemental analysis of geological samples from Na to U. However, it has seldom been applied for quantitative determination of oxidation states of elements in complex matrices. In this study, we present a method to determine the oxidation states of iron in geological samples by WD‐XRF. We used the FeLα1,2 fluorescence line as a tool for iron speciation and Fe(II)/Fetotal ratio determination. We found that the normalized intensity (peak height) of FeLα1,2 fluorescence line was linearly correlated with the spin multiplicity (2S + 1) of ferrous and ferric content in the samples. To account for the matrix effects of chemical environment (matrix and chemical bonding) on FeLα1,2 fluorescence line, we introduced a chemical index factor (μ) that enabled accurate determination of Fe(II)/Fetotal ratio in different types of geological samples. The method was validated using international certified reference materials and their mixtures and obtained promising results, with only 6 out of 55 determinations showing relative error more than 5% of the certified values.

Intracellular Fate of Sub-Toxic Concentration of Functionalized Selenium Nanoparticles in Aggressive Prostate Cancer Cells

Selenium 0 (Se0) is a powerful anti-proliferative agent in cancer research. We investigated the impact of sub-toxic concentrations of Se0 functionalized nanoparticles (SeNPs) on prostate cancer PC-3 cells and determined their intracellular localization and fate. An in-depth characterization of functionalized selenium nanoparticles composition is proposed to certify that no chemical bias relative to synthesis issues might have impacted the study. Selenium is an extremely diluted element in the biological environment and therefore requires high-performance techniques with a very low detection limit and high spatial resolution for intracellular imaging. This was explored with state-of-the-art techniques, but also with cryopreparation to preserve the chemical and structural integrity of the cells for spatially resolved and speciation techniques. Monodisperse solutions of SeNPs capped with bovine serum albumin (BSA) were shown to slow down the migration capacity of aggressive prostate cancer cells compared to polydisperse solutions of SeNPs capped with chitosan. BSA coating could prevent interactions between the reactive surface of the nanoparticles and the plasma membrane, mitigating the generation of reactive oxygen species. The intracellular localization showed interaction with mitochondria and also a localization in the lysosome-related organelle. The SeNPs-BSA localization in mitochondria constitute a possible explanation for our result showing a very significant dampening of the PC-3 cell proliferation capabilities. The purpose of the use of sublethal compound concentrations was to limit adverse effects resulting from high cell death to best evaluate some cellular changes and the fate of these SeNPs on PC-3. Our findings provide new insight to further study the various mechanisms of cytotoxicity of SeNPs.

Boiling point modeling for petroleum speciation data

An empirical model is presented for generating the boiling curve of a petroleum sample based on parameters that are experimentally available using typical speciation techniques. The approach estimates the boiling point distribution of the detected components and allows a comparison with the simulated distillation profile of the sample. The model is shown to predict the boiling behavior of the speciation-derived average components in crude oil distillation fractions, which match the measured average distillation temperature of the fractions. The model is then applied to generate boiling distributions, based on mass spectrometric and gas chromatographic speciation data, which match the measured simulated-distillation curves with less than 20 °C difference. The model is also applied to the isolated fraction of saturated compounds, where the modeled boiling profile matches well with the measured distillation profile of the entire sample. This confirms that the model, although built using Fourier transform ion cyclotron resonance mass spectrometry data of aromatic compounds, extends to data obtained using comprehensive 2-dimensional gas chromatography, and also describes the boiling behavior of saturated compounds speciated by field desorption time of flight mass spectrometry. Consequently, the modeled boiling distribution enables an assessment of how well a speciation measurement describes the sample, and provides an estimation of lower and higher-boiling portions that have been omitted in the data set.

X-ray absorption fine structure (XAFS)-based radionuclide research at the KIT Light Source

Abstract. In the past two decades, X-ray absorption spectroscopy (XAS) and related synchrotron-based radionuclide speciation techniques have become indispensable, supporting open issues in fundamental radiochemistry and nuclear waste disposal alike. Physicochemical structure information – encoded in the element-specific X-ray absorption fine structure (XAFS) – is obtained by the precise determination of the linear mass absorption coefficient μ(E) of a specimen in an X-ray energy window ΔE encompassing an electronic bonding level of a selected atom type. The characteristic modulations of μ(E) in the vicinity of an “absorption edge” (i.e., the steeply rising absorption probability of photons tuned to the binding energy of inner shell “core” electrons) are attributed to electronic transitions into unoccupied states due to the photoelectric effect. While absorption features close to the edge (arising from excitations into molecular orbitals or empty band structure levels close to the Fermi level) are generally denoted as an X-ray absorption near-edge structure (XANES), the scattering states at higher excitation energies are causing the well-known extended X-ray absorption fine structure (EXAFS). EXAFS oscillations of the post-edge μ(E) are caused by the periodicity of the constructive and destructive interference of outbound and backscattered inbound photoelectron waves (superimposing at the absorbing atom site) when continuously increasing the excitation energy. Quantitative analysis of EXAFS data based on electron scattering theory is a well-established short-range structural probe, providing precise values of interatomic distances (between the absorber atom and its neighbors) and additional information on the type, number, and ordering of neighbor atoms within a local cluster. Recent significant advancements in the quantum theoretical description of core-excited final states have been successful in overcoming persisting ambiguities in XANES data interpretation. Meanwhile, although there are more than 50 synchrotron radiation centers operational in the world, facilities with specialized beamline infrastructure and safety protocols to allow experiments on radioactive samples with activities beyond the exemption limits are still scarce. At the KIT Light Source (at the Karlsruhe Institute of Technology, Karlsruhe, Germany), the Institute for Nuclear Waste Disposal (Institut für Nukleare Entsorgung, INE) operates two beamline end-stations dedicated to the investigation of radionuclide materials by XAFS spectroscopy and related techniques, i.e., the INE-Beamline (operational since 2005) and the ACT station of the CAT-ACT (CATalysis and ACTinide) wiggler beamline (operational since 2016). Samples with total activities amounting to 1.0×106 times the isotope specific exemption limits and 200 mg of fissile isotopes 235U and 239Pu are feasible at both beamlines. Highly versatile detection systems and sample holders – generally avoiding extensive shielding or sample handling in a glove box – have been conceived since the initial commissioning of the beamlines and have enabled unique XAFS measurements such as the first ever investigation of aqueous technetium species at the Tc L3 edge. Investigations of highly radioactive specimens (e.g., spent nuclear fuel or nuclear waste glass fragments) are feasible, regardless of the actual contact dose rate if the radiation field is limited to a few microsieverts per hour at the edge of the experimental table.

Interplay of Metallome and Metabolome in Amyotrophic Lateral Sclerosis: A Study on Cerebrospinal Fluid of Patients Carrying Disease-Related Gene Mutations.

Amyotrophic lateral sclerosis (ALS) is a lethal progressive neurodegenerative disease, characterized by a loss of function of upper and lower motor neurons. This study aimed to explore probable pathological alterations occurring in individuals with ALS compared to neurologically healthy controls through the analysis of cerebrospinal fluid (CSF), a medium, which directly interacts with brain parenchyma. A total of 7 ALS patients with disease-associated mutations (ATXN2, C9ORF72, FUS, SOD1, and TARDBP) and 13 controls were included in the study. Multiple analytical approaches were employed, including metabolomic and metallomics profiling, as well as genetic screening, using CSF samples obtained from the brain compartment. Data analysis involved the application of multivariate statistical methods. Advanced hyphenated selenium and redox metal (iron, copper, and manganese) speciation techniques and nontargeted Fourier transform ion cyclotron resonance mass spectrometry-based metabolomics were used for data acquisition. Nontargeted metabolomics showed reduced steroids, including sex hormones; additionally, copper and manganese species were found to be the most relevant features for ALS patients. This indicates a potential alteration of sex hormone pathways in the ALS-affected brain, as reflected in the CSF.

Differential detection of sheep and goat meat using duplex real-time PCR and high-resolution melt analysis

Authenticity in meat and meat products is of paramount importance in preventing adulteration and ensuring food safety. Since morphologically indistinct samples like sheep and goat meat requires accurate and sensitive differentiation, we developed and validated a duplex real-time polymerase chain reaction (qPCR) assay with high-resolution melt analysis (HRMA) for simultaneous identification of sheep and goat meat. Species-specific amplicons with melting temperature of 78 °C for goat and 80 °C for sheep (with associated standard errors) was identified. The assay was optimized for basic PCR parameters and the HRMA detection was standardized based on melt curve shape, color and inflexion points. The absolute limit of detection (LODabs) and limit of quantification (LOQ) of the assay were found to be 0.39 ng and 0.78 ng of target DNA respectively. A sensitivity of 0.1% was obtained for both sheep and goat meat. The relative limit of detection (LODrel) was also found to be 5%. The linearity and efficiency were evaluated in both simplex and duplex assays. The assay applicability was evaluated using proficiency test samples and commercially available raw and processed meat samples. The obtained results showed that this closed-tube qPCR-HRMA method can be a rapid and sensitive detection technique for meat speciation.

Nanoscale heterogeneity of arsenic and selenium species in coal fly ash particles: analysis using enhanced spectroscopic imaging and speciation techniques.

Coal combustion byproducts are known to be enriched in arsenic (As) and selenium (Se). This enrichment is a concern during the handling, disposal, and reuse of the ash as both elements can be harmful to wildlife and humans if mobilized into water and soils. The leaching potential and bioaccessibility of As and Se in coal fly ash depends on the chemical forms of these elements and their association with the large variety of particles that comprise coal fly ash. The overall goal of this research was to determine nanoscale and microscale solid phase mineral associations and oxidation states of As and Se in fly ash. We utilized nanoscale 2D imaging (30-50 nm spot size) with the Hard X-ray Nanoprobe (HXN) in combination with microprobe X-ray capabilities (∼5 μm resolution) to determine the As and Se elemental associations. Speciation of As and Se was also measured at the nano- to microscale with X-ray absorption spectroscopy. The enhanced resolution of HXN showed As and Se as either diffusely located around or comingled with Ca- and Fe-rich particles. The results also showed nanoparticles of Se attached to the surface of fly ash grains. Overall, a comparison of As and Se species across scales highlights the heterogeneity and complexity of chemical associations for these trace elements of concern in coal fly ash.

Soil properties influence the toxicity and availability of Zn from ZnO nanoparticles to earthworms

To develop models that support site-specific risk assessment for nanoparticles (NPs), a better understanding of how NP transformation processes, bioavailability and toxicity are influenced by soil properties is needed. In this study, the influence of differing soil properties on the bioavailability and toxicity of zinc oxide (ZnO) NPs and ionic Zn to the earthworm Eisenia fetida was investigated. Earthworms were exposed to ZnO_NPs and ionic Zn, between 100 and 4400 mg Zn/kg, in four different natural soils (organic matter content: 1.8–16.7%, soil pH: 5.4–8.3, representing sandy loam to calcareous soils). Survival and reproduction were assessed after 28 and 56 days, respectively. Zn concentrations in soil pore waters were measured while labile concentrations of Zn were measured using an in-situ dynamic speciation technique (diffusive gradient in thin films, DGT). Earthworm Zn tissue concentrations were also measured. Soil properties influenced earthworm reproduction between soil controls, with highest reproductive output in soils with pH values of 6–7. Toxicity was also influenced by soil properties, with EC50s based on total Zn in soil ranging from 694 to >2200 mg Zn/kg for ZnO_NP and 277–734 mg Zn/kg for ionic Zn. Soil pore water and DGT measurements showed good agreement in the relative amount of Zn extracted across the four soils. Earthworms exposed to ZnO_NPs survived higher Zn concentrations in the soils and had higher tissue concentrations compared with ionic Zn exposures, particularly in the high organic content calcareous soil. These higher tissue concentrations in ZnO_NP exposed earthworm could have consequences for the persistence and trophic mobility of Zn in terrestrial systems and need to be further investigated to elucidate if there any longer-term risks associated with sustained input of ZnO_NP to soil.

Multivariate versus machine learning-based classification of rapid evaporative Ionisation mass spectrometry spectra towards industry based large-scale fish speciation

Detection and prevention of fish food fraud are of ever-increasing importance, prompting the need for rapid, high-throughput fish speciation techniques. Rapid Evaporative Ionisation Mass Spectrometry (REIMS) has quickly established itself as a powerful technique for the instant in situ analysis of foodstuffs. In the current study, a total of 1736 samples (2015–2021) - comprising 17 different commercially valuable fish species - were analysed using iKnife-REIMS, followed by classification with various multivariate and machine learning strategies. The results demonstrated that multivariate models, i.e. PCA-LDA and (O)PLS-DA, delivered accuracies from 92.5 to 100.0%, while RF and SVM-based classification generated accuracies from 88.7 to 96.3%. Real-time recognition on a separate test set of 432 samples (2022) generated correct speciation between 89.6 and 99.5% for the multivariate models, while the ML models underperformed (22.3–95.1%), in particular for the white fish species. As such, we propose a real-time validated modelling strategy using directly amenable PCA-LDA for rapid industry-proof large-scale fish speciation.

The Toxicological Risk Assessment (TRA) of Total Chromium Impurities in Menthae piperitae tinctura (Mentha x piperita L., folium) Available in Polish Pharmacies Including Regulatory Approaches with Special Emphasis of Cr Speciation and Genotoxicity

Chromium is pharmacologically active and is not an essential element but is still very intriguing and demanding from the point of view of toxicological risk assessment. Especially as an elemental impurity in final pharmaceuticals. The aim of this article is toxicological risk assessment (TRA) of total Cr impurities in Menthae piperitae tinctura (Mentha x piperita L., folium) available in Polish pharmacies including triple approach. Obtained raw/basal results shows that impurities of total Cr impurities were present in all investigated pharmaceutical with Mentha x piperita L., folium. but at a relatively low level (in the range: 0.39–2.14 µg/L). The regulatory strategy based on the ICH Q3D (R1) elemental impurities guidelines confirms that all the requirements of the analyzed products meet the European Medicine Agency (EMA) requirements. Obtained results obtained show that the estimated maximum daily exposure to Cr (ng/day) are variable between the samples (0.521–3.792 ng/day), but at a relatively low level (< 4.0 ng/day).The final step confirms the safety of analyzed pharmaceuticals, because the comparison of the estimated results with the oral PDE value for Cr in final drugs suggested by the ICH Q3D guideline (10,700 µg/day) show that all the products are below this value. The approach based on the margin of exposure (MoE) for children and adults also confirms the safety of all the products with Mentha x piperita L., (in all cases MoE > > 10 000). It can be concluded that all the samples analyzed should not represent any health hazard to patients due to Cr impurities. To our knowledge, this is the first study about application of comprehensive TRA of total Cr impurities in phytopharmaceuticals with Mentha x piperita L., folium available in European pharmacies. Additionally, we confirm the safety of Cr impurities by applying triple regulatory strategy without the application of an expansive and demanding HPLC-ICP-MS technique for Cr speciation.

Prevalence and speciation of malaria parasites among patients attending Ahoada and Amassoma Communities’ general hospitals in Rivers and Bayelsa State, Nigeria

Malaria is one of the deadly diseases recognized globally in children and adults especially in Nigeria and some African countries. This study was designed to determine Prevalence and Speciation of malaria parasites from patients attending Ahoada and Amassoma Communities’ General Hospitals in Rivers and Bayelsa States respectively. A total of two hundred (200) venous blood collected from Amassoma [101(40 males, 61 Female) and Ahoada [99; 46male, 53 females) into sterile Ethylene Diamine Tetra Acetic Acid (EDTA) bottles from patients attending the above mentioned General Hospitals were immediately transferred to Medical Microbiology Laboratory, Department of Medical Laboratory Science for analysis using Microscopy by staining, Rapid Diagnostic Tests kits (SD Bioline kits; Pf/pan and Pf specific kit) and molecular analysis by Polymerase Chain Reaction (PCR) technique. Twenty (20) positive samples were subjected to Polymerase Chain Reaction Technique for Speciation. Findings showed 141(70.5%) subjects positive to malaria parasites comprised of Children 25(12.5%) between age of 6 and 17 years, adult female 63(31.5%) and male 53(26.5%) between the age of 18 and 90. Also noted were subjects with age ranges of 6-10, 21-25, 51-55 and 86-90 years had the highest percentage prevalence of 100%, followed by 41-45 years with a prevalence rate of 83.3% and the least prevalence was 33.3% from 56-60 years. Observations showed that out of 20 positive samples subjected to molecular diagnosis for Speciation, 17(85%) were Plasmodium falciparum, thus revealing their predominance of 90%. In conclusion, Plasmodium falciparum was the predominant parasite among Plasmodia species responsible for malaria infection in both Rivers and Bayelsa States. Female and children are vulnerable to malaria infection as revealed in this study. Therefore, the government is encouraged to take women and children’s health into consideration by conducting malaria test for them weekly to enable prompt treatment where applicable.

Determination of trace metals in vegetables using ICP-MS

Determination of trace metals in vegetables using ICP-MS

Review about Powerful Combinations of Advanced and Hyphenated Sample Introduction Techniques with Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) for Elucidating Trace Element Species in Pathologic Conditions on a Molecular Level.

Element analysis in clinical or biological samples is important due to the essential role in clinical diagnostics, drug development, and drug-effect monitoring. Particularly, the specific forms of element binding, actual redox state, or their spatial distribution in tissue or in single cells are of interest in medical research. This review summarized exciting combinations of sophisticated sample delivery systems hyphenated to inductively coupled plasma-mass spectrometry (ICP-MS), enabling a broadening of information beyond the well-established outstanding detection capability. Deeper insights into pathological disease processes or intracellular distribution of active substances were provided, enabling a better understanding of biological processes and their dynamics. Examples were presented from spatial elemental mapping in tissue, cells, or spheroids, also considering elemental tagging. The use of natural or artificial tags for drug monitoring was shown. In the context of oxidative stress and ferroptosis iron, redox speciation gained importance. Quantification methods for Fe2+, Fe3+, and ferritin-bound iron were introduced. In Wilson’s disease, free and exchangeable copper play decisive roles; the respective paragraph provided information about hyphenated Cu speciation techniques, which provide their fast and reliable quantification. Finally, single cell ICP-MS provides highly valuable information on cell-to-cell variance, insights into uptake of metal-containing drugs, and their accumulation and release on the single-cell level.

Biological Samples Preparation for Speciation at Cryogenic Temperature using High-Resolution X-Ray Absorption Spectroscopy.

The study of elements with X-ray absorption spectroscopy (XAS) is of particular interest when studying the role of metals in biological systems. Sample preparation is a key and often complex procedure, particularly for biological samples. Although X-ray speciation techniques are widely used, no detailed protocol has been yet disseminated for users of the technique. Further, chemical state modification is of concern, and cryo-based techniques are recommended to analyze the biological samples in their near-native hydrated state to provide the maximum preservation of chemical integrity of the cells or tissues. Here, we propose a cellular preparation protocol based on cryo-preserved samples. It is demonstrated in a high energy resolution fluorescence detected X-ray absorption spectroscopy study of selenium in cancer cells and a study of iron in phytoplankton. This protocol can be used with other biological samples and other X-ray techniques that can be damaged by irradiation.

Recent developments in microextraction techniques for detection and speciation of heavy metals

Analysis of heavy metals and their species in complex samples such as environment, biology and medicine is be of paramount importance due to their toxicity, persistence, and bioaccumulation. Considering the complexity of the sample matrix and the low concentration of heavy metals, sample preparation step should be exerted before analysis. Microextraction techniques have received extensive attention due to its miniaturization, quickness, low cost, environmental friendliness, and satisfactory extraction performance. So far, various formats based on microextraction techniques have been developed and applied to entrap heavy metals and related species. This review mainly concentrates on the recent development and applications of microextraction techniques including solvent-based liquid-phase microextraction and sorbent-based solid-phase microextraction for the detection and speciation of heavy metals in water, food, sediment, soil, hair, urine, and serum samples.

Stable Isotope Fractionation of Metals and Metalloids in Plants: A Review.

This work critically reviews stable isotope fractionation of essential (B, Mg, K, Ca, Fe, Ni, Cu, Zn, Mo), beneficial (Si), and non-essential (Cd, Tl) metals and metalloids in plants. The review (i) provides basic principles and methodologies for non-traditional isotope analyses, (ii) compiles isotope fractionation for uptake and translocation for each element and connects them to physiological processes, and (iii) interlinks knowledge from different elements to identify common and contrasting drivers of isotope fractionation. Different biological and physico-chemical processes drive isotope fractionation in plants. During uptake, Ca and Mg fractionate through root apoplast adsorption, Si through diffusion during membrane passage, Fe and Cu through reduction prior to membrane transport in strategy I plants, and Zn, Cu, and Cd through membrane transport. During translocation and utilization, isotopes fractionate through precipitation into insoluble forms, such as phytoliths (Si) or oxalate (Ca), structural binding to cell walls (Ca), and membrane transport and binding to soluble organic ligands (Zn, Cd). These processes can lead to similar (Cu, Fe) and opposing (Ca vs. Mg, Zn vs. Cd) isotope fractionation patterns of chemically similar elements in plants. Isotope fractionation in plants is influenced by biotic factors, such as phenological stages and plant genetics, as well as abiotic factors. Different nutrient supply induced shifts in isotope fractionation patterns for Mg, Cu, and Zn, suggesting that isotope process tracing can be used as a tool to detect and quantify different uptake pathways in response to abiotic stresses. However, the interpretation of isotope fractionation in plants is challenging because many isotope fractionation factors associated with specific processes are unknown and experiments are often exploratory. To overcome these limitations, fundamental geochemical research should expand the database of isotope fractionation factors and disentangle kinetic and equilibrium fractionation. In addition, plant growth studies should further shift toward hypothesis-driven experiments, for example, by integrating contrasting nutrient supplies, using established model plants, genetic approaches, and by combining isotope analyses with complementary speciation techniques. To fully exploit the potential of isotope process tracing in plants, the interdisciplinary expertise of plant and isotope geochemical scientists is required.

Implementation of cryogenic tender X-ray HR-XANES spectroscopy at the ACT station of the CAT-ACT beamline at the KIT Light Source.

The ACT experimental station of the CAT-ACT wiggler beamline at the Karlsruhe Institute of Technology (KIT) Light Source is dedicated to the investigation of radionuclide materials with radioactivities up to 1000000 times the exemption limit by various speciation techniques applying monochromatic X-rays. In this article, the latest technological developments at the ACT station that enable high-resolution X-ray absorption near-edge structure (HR-XANES) spectroscopy for low radionuclide loading samples are highlighted - encompassing the investigation of actinide elements down to 1 p.p.m. concentration - combined with a cryogenic sample environment reducing beam-induced sample alterations. One important part of this development is a versatile gas tight plexiglass encasement ensuring that all beam paths in the five-analyzer-crystal Johann-type X-ray emission spectrometer run within He atmosphere. The setup enables the easy exchange between different experiments (conventional X-ray absorption fine structure, HR-XANES, high-energy or wide-angle X-ray scattering, tender to hard X-ray spectroscopy) and opens up the possibility for the investigation of environmental samples, such as specimens containing transuranium elements from contaminated land sites or samples from sorption and diffusion experiments to mimic the far field of a breached nuclear waste repository.

Investigation of diffusion and binding properties of uranium in the diffusive gradients in thin-films technique

Environmental context Monitoring uranium concentrations and speciation in aquatic systems is important for pollution control and for environmental studies. Although an in situ speciation technique based on diffusion and uptake of uranium has been developed, known as DGT, there were uncertainties over some parameters affecting the accuracy of the measurements. This study resolved those uncertainties by investigating diffusion and binding properties of uranium in DGT and provided confidence in monitoring uranium in the environment. Rationale Diffusive gradients in thin-films (DGT) ha been used for uranium speciation measurements since 2006, but interpretational difficulties have arisen due to uncertainties in the pH dependence of U diffusion coefficients (D) within the diffusive gel. This work tested the hypothesis that differences in measured D values between laboratories are due to methodological artifacts. Methodology The properties of uranium binding and diffusion of U within DGT were systematically investigated at different conditions between pH 3–8 and ionic strength from 1 to 500 mmol L−1. Previous uncertainties were attributed to loss of U by adsorption within the diffusion cell, identified by mass balance calculations, and a binding efficiency dependent on the type of binding gel. Results The diffusion coefficient in an agarose cross-linked polyacrylamide gel measured using Metsorb DGT of 5.26 ± 0.17 × 10−6 cm2 s−1 agreed well with both values obtained using a pre-conditioned diffusion cell (&lt; 7% difference) and by modelling. The binding efficiencies for Chelex DGT (BChelex = 0.86–0.89) and Fe-oxide DGT (BFe-oxide = 0.64 were smaller than for Metsorb DGT (BMetsorb = 1). No significant differences were found for BChelex at different pH. Discussion This work demonstrated that the diffusion coefficient of uranium is independent of pH and the binding gel used, provided the binding efficiency (B) is taken into account. These findings indicate that DGT equipped with either Metsorb or Chelex binding gels should be capable of measuring U for a wide range of environmental conditions provided the appropriate diffusion coefficients and binding efficiencies are used.