Rare earth element identification and quantification in millimetre-sized Ryugu rock fragments from the Hayabusa2 space mission.

Millimetre-sized primordial rock fragments originating from asteroid Ryugu were investigated using high energy X-ray fluorescence spectroscopy, providing 2D and 3D elemental distribution and quantitative composition information on the microscopic level. Samples were collected in two phases from two sites on asteroid Ryugu and safely returned to Earth by JAXA's asteroid explorer Hayabusa2, during which time the collected material was stored and maintained free from terrestrial influences, including exposure to Earth's atmosphere. Several grains of interest were identified and further characterised to obtain quantitative information on the rare earth element (REE) content within said grains, following a reference-based and computed-tomography-assisted fundamental parameters quantification approach. Several orders of magnitude REE enrichments compared to the mean CI chondrite composition were found within grains that could be identified as apatite phase. Small enrichment of LREE was found for dolomite grains and slight enrichment or depletion for the general matrices within the Ryugu rock fragments A0055 and C0076, respectively. Supplementary Information: The online version contains supplementary material available at 10.1186/s40623-022-01705-3.

Highly Sensitive Nondestructive Rare Earth Element Detection by Means of Wavelength-Dispersive X-ray Fluorescence Spectroscopy Enabled by an Energy Dispersive pn-Charge-Coupled-Device Detector.

Detection of rare earth elements (REE) is commonly performed with destructive techniques such as (LA)-ICPMS or coupled to a destructive sample preparation. When investigating unique geological samples, such as cometary, asteroidal, or interstellar material from sample return missions or inclusions in deep Earth diamonds, a nondestructive method is preferred. The presented nondestructive highly sensitive wavelength-dispersive X-ray fluorescence spectroscopy (WD-XRF) technique is designed to measure the L-lines of REE between 4.5 and 7 keV with a sensitivity down to the ppm level. REE fluorescence L-lines are often only separated by a few eV from neighboring XRF-lines and cannot be resolved by an energy dispersive approach especially in the presence of transition metal K-lines. In our spectrometer the characteristic X-rays emitted by the sample are dispersed by a fixed Ge(111) analyzer crystal over the active area of an energy dispersive pn-charge-coupled-device (pnCCD) detector, enabling high energy resolution detection of X-rays differentiated by their corresponding Bragg angles. The use of an energy-dispersive 2D detector enables the simultaneous acquiring of XRF-lines while eliminating any ambiguities due to potential contribution from higher order diffraction effects or other diffraction planes and thereby increases the sensitivity by reducing the (scatter) background. This detection method shows an energy resolution of 12 eV for the Ti-Kα fluorescence line and has a sensitivity down to 0.50 ppm for REE L-lines. The method was optimized specifically for the nondestructive analysis of inclusions in deep Earth diamonds, yielding in situ quantitative information about up-to-now inaccessible elemental (REE) composition patterns together with the more abundant transition metals like Ti, Cr, Mn, and Fe. This information is of great importance to decipher the role that deep Earth plays in the global carbon and fluid cycle.

Investigation of (micro-)meteoritic materials at the new hard X-ray imaging PUMA beamline for heritage sciences.

At the French synchrotron facility SOLEIL, a new X-ray imaging facility PUMA (Photons Utilisés pour les Matériaux Anciens) has been made available to scientific communities studying materials from cultural heritage. This new instrument aims to achieve 2D and 3D imaging with microscopic resolution, applying different analytical techniques including X-ray fluorescence spectroscopy (XRF), X-ray absorption spectroscopy (XAS), X-ray diffraction and phase-contrast imaging. In order to discover its capabilities a detailed analytical characterization of this beamline as an analytical and imaging tool is deemed necessary. In this work, (confocal) XRF and XAS analyses are demonstrated using the Seymchan pallasite meteorite and an Antarctic unmelted micrometeorite as case studies. The obtained spatial resolution (2 µm × 3 µm) and sensitivity (detection limits <10 p.p.m. for 1 s acquisition at 18 keV) show that PUMA is a competitive state-of-the-art beamline, providing several high-profile and high-in-demand analytical methods while maintaining applicability towards a wide range of heritage-oriented sciences.

Correlations between As in Earthworms' Coelomic Fluid and As Bioavailability in Highly Polluted Soils as Revealed by Combined Laboratory X-ray Techniques.

Combined X-ray-based spectroscopy techniques were applied to investigate arsenic (As) bioaccumulation in earthworms (Eisenia andrei) exposed to six field-collected polluted soils (58-13 330 mg As kg-1). After 14 days of exposure to the arsenious soils, the As distribution in earthworms was examined by micro-X-ray fluorescence spectroscopy (µXRF), after epoxy resin embedding and preparing thin sections. Similar to µXRF data, XRF-computed tomography (XRF-CT) confirmed As accumulation in the coelom of intact earthworms. Therefore, total-reflection XRF was used to determine total As within both the whole earthworm's body (AsE) and coelomic fluid extracts (AsF). Bioaccumulation data (AsE and AsF) were thereafter evaluated in relation to total As concentration in soils (AsT) and to As mobile fraction in soils. A significant linear correlation (R2 = 0.97) was found between AsE and AsF, indicating that the As sequestrated into the coelomic fluid may reflect the total body concentration. Therefore, we may conclude that the As concentration in the coelomic fluid can be used as an index of As availability. This paper demonstrates that by combining different laboratory X-ray analytical techniques, compartmentalization and bioavailability of potentially toxic elements can be visualized and quantified within indicator-living organisms, thus contributing to an improved risk assessment for contaminated soils.

Cellular Fractionation and Nanoscopic X-Ray Fluorescence Imaging Analyses Reveal Changes of Zinc Distribution in Leaf Cells of Iron-Deficient Plants.

Multilevel interactions among nutrients occur in the soil-plant system. Among them, Fe and Zn homeostasis in plants are of great relevance because of their importance for plant and human nutrition. However, the mechanisms underlying the interplay between Fe and Zn in plants are still poorly understood. In order to elucidate how Zn interacts with Fe homeostasis, it is crucial to assess Zn distribution either in the plant tissues or within the cells. In this study, we investigated the subcellular Zn distribution in Fe-deficient leaf cells of cucumber plants by using two different approaches: cellular fractionation coupled with inductively coupled plasma mass spectrometry (ICP/MS) and nanoscopic synchrotron X-ray fluorescence imaging. Fe-deficient leaves showed a strong accumulation of Zn as well as a strong alteration of the organelles' ultrastructure at the cellular level. The cellular fractionation-ICP/MS approach revealed that Zn accumulates in both chloroplasts and mitochondria of Fe deficient leaves. Nano-XRF imaging revealed Zn accumulation in chloroplast and mitochondrial compartments, with a higher concentration in chloroplasts. Such results show that (i) both approaches are suitable to investigate Zn distribution at the subcellular level and (ii) cellular Fe and Zn interactions take place mainly in the organelles, especially in the chloroplasts.

Polycapillary Optics Based Confocal Micro X-ray Fluorescence and X-ray Absorption Spectroscopy Setup at The European Synchrotron Radiation Facility Collaborative Research Group Dutch-Belgian Beamline, BM26A.

A novel plug-and-play setup based on polycapillary X-ray optics enables three-dimensional (3D) confocal X-ray fluorescence (XRF) and X-ray absorption spectroscopy down to 8 × 8 × 11 µm3 (17 keV) at the European Synchrotron Radiation Facility Collaborative Research Group Dutch-Belgian Beamline, BM26A. A complete description and analytical characterization is presented, together with two recently performed experimental cases. In Deep Earth diamond São Luiz-Frankfurt am Main 16, an olivine-rich inclusion was mapped with full 3D XRF elemental imaging. The preliminary tests on Iron Gall ink contained in an historical document, a letter from the court of King Philip II of Spain, reveal both the delicate nature of Iron Gall ink and the lack of Fe-Ni chemical bonding.

Integrated Three-Dimensional Microanalysis Combining X-Ray Microtomography and X-Ray Fluorescence Methodologies.

A novel 3D elemental and morphological analysis approach is presented combining X-ray computed tomography (µCT), X-ray fluorescence (XRF) tomography, and confocal XRF analysis in a single laboratory instrument (Herakles). Each end station of Herakles (µCT, XRF-CT, and confocal XRF) represents the state-of-the-art of currently available laboratory techniques. The integration of these techniques enables linking the (quantitative) spatial distribution of chemical elements within the investigated materials to their three-dimensional (3D) internal morphology/structure down to 1-10 µm resolution level, which has not been achieved so-far using laboratory X-ray techniques. The concept of Herakles relies strongly on its high precision (around 100 nm) air-bearing motor system that connects the different end-stations, allowing combined measurements based on the above X-ray techniques while retaining the coordinate system. In-house developed control and analysis software further ensures a smooth integration of the techniques. Case studies on a Cu test pattern, a Daphnia magna model organism and a perlite biocatalyst support material demonstrate the attainable resolution, elemental sensitivity of the instrument, and the strength of combining these three complementary methodologies.

Application toward Confocal Full-Field Microscopic X-ray Absorption Near Edge Structure Spectroscopy.

Using X-ray absorption near edge structure (XANES) spectroscopy, information on the local chemical structure and oxidation state of an element of interest can be acquired. Conventionally, this information can be obtained in a spatially resolved manner by scanning a sample through a focused X-ray beam. Recently, full-field methods have been developed to obtain direct 2D chemical state information by imaging a large sample area. These methods are usually in transmission mode, thus restricting the use to thin and transmitting samples. Here, a fluorescence method is displayed using an energy-dispersive pnCCD detector, the SLcam, characterized by measurement times far superior to what is generally applicable. Additionally, this method operates in confocal mode, thus providing direct 3D spatially resolved chemical state information from a selected subvolume of a sample, without the need of rotating a sample. The method is applied to two samples: a gold-supported magnesia catalyst (Au/MgO) and a natural diamond containing Fe-rich inclusions. Both samples provide XANES spectra that can be overlapped with reference XANES spectra, allowing this method to be used for fingerprinting and linear combination analysis of known XANES reference compounds.

Assessment of Ovarian Cancer Tumors Treated with Intraperitoneal Cisplatin Therapy by Nanoscopic X-ray Fluorescence Imaging.

Ovarian cancer is amongst the most common types of cancer in women, with a relatively low overall cure rate of approximately 30%. This is therefore an important incentive to urge for further research in order to maximize the chances of survival for these patients. Intraperitoneal chemotherapy with Cisplatin is an effective treatement for ovarian cancer; however, many questions still remain concerning the ideal treatment protocol and tumor resistance towards the drug, which should be resolved for optimal application of this therapy. For the first time in-vivo grown tumors treated with both hyper- and normothermic intraperitoneal chemotherapy have been studied using nano-XRF spectroscopy to examine the platinum (Pt) distribution within the analyzed tissues. These measurements prove Pt resides predominantly outsides the cancer cells in the stroma of the tissue. These findings indicate the resistance mechanism of the cancer cells prevents Cisplatin from diffusing through their cell membranes. This is an important addition to the existing knowledge on the resistance mechanism providing insights which might help to overcome this effect. In our aim to find the optimal treatment protocol, no significant differences were found between the two examined procedures. A more extensive data set will be needed to draw definite conclusions.

Laboratory Scale X-ray Fluorescence Tomography: Instrument Characterization and Application in Earth and Environmental Science.

A new laboratory scale X-ray fluorescence (XRF) imaging instrument, based on an X-ray microfocus tube equipped with a monocapillary optic, has been developed to perform XRF computed tomography experiments with both higher spatial resolution (20 µm) and a better energy resolution (130 eV @Mn-K(α)) than has been achieved up-to-now. This instrument opens a new range of possible applications for XRF-CT. Next to the analytical characterization of the setup by using well-defined model/reference samples, demonstrating its capabilities for tomographic imaging, the XRF-CT microprobe has been used to image the interior of an ecotoxicological model organism, Americamysis bahia. This had been exposed to elevated metal (Cu and Ni) concentrations. The technique allowed the visualization of the accumulation sites of copper, clearly indicating the affected organs, i.e. either the gastric system or the hepatopancreas. As another illustrative application, the scanner has been employed to investigate goethite spherules from the Cretaceous-Paleogene boundary, revealing the internal elemental distribution of these valuable distal ejecta layer particles.

Development and Applications of a Laboratory Micro X-ray Fluorescence (µXRF) Spectrometer Using Monochromatic Excitation for Quantitative Elemental Analysis.

The analytical characterization and an application example of a novel laboratory X-ray fluorescence (µXRF) microprobe is presented, which combines monochromatic, focused X-ray beam excitation with a high-performance silicon drift detector (SDD) and two-dimensional/three-dimensional (2D/3D) scanning capability. Because of the monochromatic excitation, below the (multiple) Compton/Rayleigh scattering peak region, the XRF spectra obtained by this laboratory spectrometer has similarly high peak-to-background ratios as those which can be obtained at synchrotron sources. However, the flux density difference between the proposed laboratory instrument and current synchrotron end stations is on the order of several orders of magnitude. As a result, sub-ppm minimum detection limits (MDL) for transition metals are obtained for a variety of sample matrices. The monochromatic excitation also allows for the efficient use of an iterative Monte Carlo simulation algorithm to obtain quantitative information on the analyzed samples. The analytical characteristics of this instrument and quantitative results, in combination with an iterative reverse Monte Carlo simulation algorithm, will be demonstrated using measurements conducted on an iron-containing meteorite.

Study of the distribution of actinides in human tissues using synchrotron radiation micro X-ray fluorescence spectrometry.

This study aims at evaluating the capabilities of synchrotron radiation micro X-ray fluorescence spectrometry (SR micro-XRF) for qualitative and semi-quantitative elemental mapping of the distribution of actinides in human tissues originating from individuals with documented occupational exposure. The investigated lymph node tissues were provided by the United States Transuranium and Uranium Registries (USTUR) and were analyzed following appropriate sample pre-treatment. Semi-quantitative results were obtained via calibration by external standards and demonstrated that the uranium concentration level in the detected actinide hot spots reaches more than 100 µg/g. For the plutonium hot spots, concentration levels up to 31 µg/g were found. As illustrated by this case study on these unique samples, SR micro-XRF has a high potential for this type of elemental bio-imaging owing to its high sensitivity, high spatial resolution, and non-destructive character.

Nanoscopic X-ray fluorescence imaging of meteoritic particles and diamond inclusions.

The new ESRF ID16B-NA Nanoanalysis beamline has been applied for the first time for XRF imaging with a resolution level down to a few tens of nanometers on rare geological materials: meteoritic fragments from achondrite NWA 6693 and diamond inclusions. The instrument proved to be an extremely valuable tool for mapping samples containing submicrometer heterogeneities. It was discovered that the track of bubblelike inclusions in NWA 6693 consists mainly of Cr-rich phases. Some inclusions containing Ni and Ca were also detected. In diamond SL05, originating from the Juina region in Brazil, multiple inclusions were analyzed with dimensions smaller than 1 µm. Raman spectrometry measurements indicated the presence of a ringwoodite inclusion in this diamond; the detection of several iron-rich inclusions justifies further investigation of this material.

Methodology toward 3D micro X-ray fluorescence imaging using an energy dispersive charge-coupled device detector.

A new three-dimensional (3D) micro X-ray fluorescence (µXRF) methodology based on a novel 2D energy dispersive CCD detector has been developed and evaluated at the P06 beamline of the Petra-III storage ring (DESY) in Hamburg, Germany. This method is based on the illumination of the investigated sample cross-section by a horizontally focused beam (vertical sheet beam) while fluorescent X-rays are detected perpendicularly to the sheet beam by a 2D energy dispersive (ED) CCD detector allowing the collection of 2D cross-sectional elemental images of a certain depth within the sample, limited only by signal self-absorption effects. 3D elemental information is obtained by a linear scan of the sample in the horizontal direction across the vertically oriented sheet beam and combining the detected cross-sectional images into a 3D elemental distribution data set. Results of the 3D µXRF analysis of mineral inclusions in natural deep Earth diamonds are presented to illustrate this new methodology.

Full-field fluorescence mode micro-XANES imaging using a unique energy dispersive CCD detector.

X-ray absorption near-edge structure (XANES) spectroscopy is a well-known nondestructive technique that allows for chemical state and local structure determination. Spatially resolved oxidation state imaging is possible performing full-field transmission mode XANES experiments, providing chemical state information on the illuminated sample area, but these experiments are limited to thin, concentrated samples. Here we present the use of a unique energy dispersive (ED) pnCCD detector, the SLcam, for full-field fluorescence mode XANES experiments, thereby significantly relaxing the constraints on sample thickness. Using this new detection methodology, spatially resolved chemical state information on millimeter-sized sample areas can be obtained with microscopic resolution in moderate measuring times (less than 15 h), obtaining a XANES profile for each of nearly 70,000 points in a single measurement without the need of scanning the sample through the beam. Besides a description of the use of this detector for micro-XANES applications, we also present the proof of concept for fluorescence mode micro-XANES using a Fe(0)/Fe2O3 model sample and a Nitisol soil sample, which was measured to obtain iron chemical state distribution information.

The combined effect of dissolved organic carbon and salinity on the bioaccumulation of copper in marine mussel larvae.

Larvae of Mytilus spp. are among the most Cu sensitive marine species. In this study we assessed the combined effect of salinity and dissolved organic carbon (DOC) on Cu accumulation on mussel larvae. Larvae were exposed for 48 h to three Cu concentrations in each of nine salinity/DOC treatments. Synchrotron radiation X-ray fluorescence was used to determine the Cu concentration in 36 individual larvae with a spatial resolution of 10 × 10 µm. Cu body burden concentrations varied between 1.1 and 27.6 µg/g DW larvae across all treatments and Cu was homogeneously distributed at this spatial resolution level. Our results indicate decreasing Cu accumulation with increasing DOC concentrations which can be explained by an increase in Cu complexation. In contrast, salinity had a nonlinear effect on Cu. This cannot be explained by copper speciation or competition processes and suggests a salinity-induced alteration in physiology.

Iron (Fe) speciation in xylem sap by XANES at a high brilliant synchrotron X-ray source: opportunities and limitations.

The development of highly brilliant synchrotron facilities all around the world is opening the way to new research in biological sciences including speciation studies of trace elements in plants. In this paper, for the first time, iron (Fe) speciation in xylem sap has been assessed by X-ray absorption near-edge structure (XANES) spectroscopy at the highly brilliant synchrotron PETRA III, beamline P06. Both standard organic Fe-complexes and xylem sap samples of Fe-deficient tomato plants were analyzed. The high photon flux provided by this X-ray synchrotron source allows on one side to obtain good XANES spectra in a reasonable amount of time (approx. 15 min for 200 eV scan) at low Fe concentrations (sub parts-per-million), while on the other hand may cause radiation damage to the sample, despite the sample being cooled by a stream of liquid nitrogen vapor. Standard Fe-complexes such as Fe(III)-succinate, Fe(III)-α-ketoglutarate, and Fe(III)-nicotianamine are somehow degraded when irradiated with synchrotron X-rays and Fe(III) can undergo photoreduction. Degradation of the organic molecules was assessed by HPLC-UV/Vis analyses on the same samples investigated by X-ray absorption spectroscopy (XAS). Fe speciation in xylem sap samples revealed Fe(III) to be complexed by citrate and acetate. Nevertheless, artifacts created by radiation damage cannot be excluded. The use of highly brilliant synchrotrons as X-ray sources for XAS analyses can dramatically increase the sensitivity of the technique for trace elements thus allowing their speciation in xylem sap. However, great attention must be paid to radiation damage, which can lead to biased results.

Spatially resolved (semi)quantitative determination of iron (Fe) in plants by means of synchrotron micro X-ray fluorescence.

Iron (Fe) is an essential element for plant growth and development; hence determining Fe distribution and concentration inside plant organs at the microscopic level is of great relevance to better understand its metabolism and bioavailability through the food chain. Among the available microanalytical techniques, synchrotron µ-XRF methods can provide a powerful and versatile array of analytical tools to study Fe distribution within plant samples. In the last years, the implementation of new algorithms and detection technologies has opened the way to more accurate (semi)quantitative analyses of complex matrices like plant materials. In this paper, for the first time the distribution of Fe within tomato roots has been imaged and quantified by means of confocal µ-XRF and exploiting a recently developed fundamental parameter-based algorithm. With this approach, Fe concentrations ranging from few hundreds of ppb to several hundreds of ppm can be determined at the microscopic level without cutting sections. Furthermore, Fe (semi)quantitative distribution maps were obtained for the first time by using two opposing detectors to collect simultaneously the XRF radiation emerging from both sides of an intact cucumber leaf.

Identification of inorganic pigments used in porcelain cards based on fusing Raman and X-ray fluorescence (XRF) data.

Raman spectroscopy and X-ray fluorescence (XRF) spectroscopy are often used as complementary techniques that are well suited for the analysis of art objects because both techniques are fast, sensitive, and noninvasive and measurements can take place in situ. In most of these studies, both techniques are used separately, in the sense that the spectra are evaluated independently and single conclusions are obtained, considering both results. This paper presents a data fusion procedure for Raman and XRF data for the characterization of pigments used in porcelain cards. For the classification of the analyzed points of the porcelain cards principal component analysis (PCA) was used. A first attempt was made to develop a new procedure for the identification of the pigments using a database containing the fused Raman-XRF data of 24 reference pigments. The results show that the classification based on the fused Raman-XRF data is significantly better than the classifications based on the Raman data or the XRF data separately.

PXRF, µ-XRF, vacuum µ-XRF, and EPMA analysis of Email Champlevé objects present in Belgian museums.

The enamel of 20 Email Champlevé objects dating between the 12th and 19th centuries was investigated by means of microscopic and portable X-ray fluorescence analysis (µ-XRF and PXRF). Seven of these objects were microsampled and the fragments were analyzed with electron probe microanalysis (EPMA) and vacuum µ-XRF to obtain quantitative data about the composition of the glass used to produce these enameled objects. As a result of the evolution of the raw materials employed to produce the base glass, three different compositional groups could be discriminated. The first group consisted of soda-lime-silica glass with a sodium source of mineral origin (with low K content) that was opacified by addition of calcium antimonate crystals. This type of glass was only used in objects made in the 12th century. Email Champlevé objects from the beginning of the 13th century onward were enameled with soda-lime-silica glass with a sodium source of vegetal origin. This type of glass, which has a higher potassium content, was opacified with SnO2 crystals. The glass used for 19th century Email Champlevé artifacts was produced with synthetic and purified components resulting in a different chemical composition compared to the other groups. Although the four analytical techniques employed in this study have their own specific characteristics, they were all found to be suitable for classifying the objects into the different chronological categories.