Uranium Single Particle Analysis for Simultaneous Fluorine and Uranium Isotopic Determinations via Laser-Induced Breakdown Spectroscopy/Laser Ablation-Multicollector-Inductively Coupled Plasma-Mass Spectrometry.

Uranyl fluoride (UO2F2) particles (<20 µm) were subjected to first-of-its-kind analysis via simultaneous laser-induced breakdown spectroscopy (LIBS) and laser ablation multi-collector inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS). Briefly, a nanosecond pulsed high-energy laser was focused onto the sample (particle) surface. In a single laser pulse, the UO2F2 particle was excited/ionized within the microplasma volume, and the emission of light was collected via fiber optics such that emission spectroscopy could be employed for the detection of uranium (U) and fluorine (F). The ablated particle was simultaneously transported into the MC-ICP-MS for high precision isotopic (i.e., 234U, 235U, and 238U) analysis. This method, LIBS/LA-MC-ICP-MS was optimized and employed to rapidly measure 80+ UO2F2 particles, which were subjected to different calcination processes, which results in varying degrees of F loss from the individual particles. In measuring the particles, the average F/U ratios for the populations treated at 100 and 500 °C were 2.78 ± 1.28 and 1.01 ± 0.50, respectively, confirming loss of F through the calcination process. The average 235U/238U on the particle populations for the 100 and 500 °C were 0.007262 (22) and 0.007231 (23), which was determined to be <0.2% from the expected value. The 234U/238U ratios on the same particles were 0.000053 (11) and 0.000050 (10) for the 100 and 500 °C, respectively, <10% from the expected value. Notably, each population was analyzed in under 5 min, demonstrating the truly rapid analysis technique presented here.

Spatially Resolved Raman Spectroscopic Investigation of Uranyl Fluoride: A Case Study in the Importance of Instrument Optimization.

Raman spectroscopy is an emerging technique for rapid and nondestructive analysis of nuclear materials for forensic and nonproliferation applications as it is a powerful tool for distinguishing multiple chemical forms of materials with similar stoichiometries. Recent developments in spectroscopic software have enabled rapid data collection with high-speed Raman spectroscopic mapping capabilities. However, some uranium-rich materials are susceptible to degradation in humid air and/or laser-induced phase transformations. To mitigate environmental or measurement-related sample degradation of potential samples of interest, we have taken a systematic approach to define optimized data collection parameters for high-throughput measurements of uranyl fluoride (UO2F2), which is an important intermediate material in the nuclear fuel cycle. First, we systematically describe the influence of optical magnification (5× to 100×), laser power, and exposure time on obtained signal for identical particles of UO2F2 and find that at low laser power and exposure times, comparable signal is obtained regardless of optical magnification. Second, we ensure sample integrity during data collection, and third, collect spectroscopic maps that employ optimized parameters to reduce the time required to obtain spatially resolved spectroscopic information. Reductions of 90% and 99% in measurement times are discussed as they relate to differences in resolving spectroscopic features of particles in identical mapping areas. During this work, we found that additional data processing options were needed and thus developed a customized Python script for importing, processing, analyzing, and visualizing Raman spectroscopic map data.

Quantifying platinum binding on protein-functionalized magnetic microparticles using single particle-ICP-TOF-MS.

This work describes an analytical procedure, single particle-inductively coupled plasma-time-of-flight-mass spectrometry (SP-ICP-TOF-MS), that was developed to determine the platinum binding efficiency of protein-coated magnetic microparticles. SP-ICP-TOF-MS is advantageous due to its ability to quasi-simultaneously detect all nuclides (7Li-242Pu), allowing for both platinum and iron (composition of magnetic microparticles) to be measured concurrently. This method subsequently allows for the differentiation between bound and unbound platinum. The 1 µm magnetic microparticles were fully characterized for their iron concentration, particle concentration, and trace element composition by bulk digestion-ICP-MS and SP-ICP-TOF-MS. The results of both approaches agreed with the certificate values. Using the single particle methodology the platinum loading was quantified to be to 0.18 ± 0.02 fg per particle and 0.32 ± 0.02 fg per particle, for the streptavidin-coated and azurin-coated microparticles, respectively. Both streptavidin-coated and the azurin-coated microparticles had a particle-platinum association of >65%. Platinum bound samples were also analyzed via bulk digestion-based ICP-MS. The bulk ICP-MS results overestimated platinum loading due to free platinum in the samples. This highlights the importance of single particle analysis for a closer inspection of platinum binding performance. The SP-ICP-TOF-MS approach offers advantages over typical bulk digestion methods by eliminating laborious sample preparation, enabling differentiation between bound/unbound platinum in a solution, and quantification of platinum on a particle-by-particle basis. The procedure presented here enables quantification of metal content per particle, which could be broadly implemented for other single particle applications.

Mapping of uranium particles on J-type swipes with microextraction-ICP-MS.

A microextraction liquid sampling system coupled to a quadrupole inductively coupled plasma-mass spectrometer (ICP-MS) was utilized to spatially discern uranium particles, isotopically, on a cellulose-based swipe material (i.e., J-type swipe). These types of swipes are often used by the International Atomic Energy Agency (IAEA) as part of their environmental sampling program. A grid was created such that extraction locations covered the center circle (n = 34 without overlapping). Uranium (U) particulates (<20 µm) of varying U isotopic abundance and chemical form (i.e., uranyl fluoride and uranyl nitrate hexahydrate) were mechanically placed on the swipes in random locations and detected via the microextraction-ICP-MS methodology. Heat maps were subsequently generated to show the placement of the particulate with their respective intensity and isotopic determination. This detection of the uranium particulates, via isotopic determination, agreed with reference values for these materials. Additionally, depleted (235U/238U = 0.002) uranium particulates were placed directly within a clay matrix, on the swipe surface, and subjected to analysis by microextraction-ICP-MS. The mapping of the swipe demonstrated, for the first time, the employment of the microextraction-ICP-MS method for extracting sample from a complex matrix, and correctly identifying the uranium isotopic composition. This example ultimately demonstrates the utility of the methodology for detecting particles of interest in complex matrices.

Microextraction-TQ-ICP-MS for the Direct Analysis of U and Pu from Cotton Swipes.

The microextraction sampling technique was integrated with triple quadrupole─inductively coupled plasma-mass spectrometry (TQ-ICP-MS) to directly sample and measure the isotopic compositions of uranium (U) and plutonium (Pu) from cotton swipes. Once extracted, the U/Pu were directed into the TQ-ICP-MS instrument for isotopic determination. Carbon dioxide (CO2) and helium (He) gases were delivered to a collision reaction cell within the ICP-MS system for ion separation. The CO2 reacts with the U+ forming UO+ which is ultimately separated from the Pu+ ions of interest in the third quadrupole. This study demonstrates direct liquid extraction of U/Pu from a solid surface and subsequent measurement by TQ-ICP-MS in <60 s. Flow rates were optimized (0.3 mL min-1 CO2 and 5 mL min-1 He) in the reaction cell of the ICP-MS system to maximize the Pu signal while minimizing U interferences (i.e., 238U+ tail and 238UH+) at m/z 239. Low levels of Pu (∼2 pg) were deposited on a cotton swipe along with U at concentrations ranging from 20 to 200 ng. The 240Pu/239Pu ratio was measured with <7% relative difference from the certified value at all U concentrations. Major and minor U isotope ratios were also measured with <4% relative difference. This highlights that the microextraction-TQ-ICP-MS method can extract a mixed U/Pu sample directly from a cotton swipe and measure both isotopic systems without chemical separation.

Initial Characterization and Optimization of the Liquid Sampling-Atmospheric Pressure Glow Discharge Ionization Source Coupled to an Orbitrap Mass Spectrometer for the Determination of Plutonium.

Plutonium measurements are essential to the nuclear forensics and safeguards community. The liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma ionization source coupled with an Orbitrap mass spectrometer is a proven platform for uranium isotope ratio determinations. This work expands the LS-APGD-Orbitrap platform capabilities by reporting the first-ever analysis of plutonium with the LS-APGD and the first-ever measurement of elemental plutonium with an Orbitrap mass spectrometer. This coupling has the potential to dramatically reduce the complex sample manipulations required for traditional analysis techniques employed for actinide isotope ratio determinations. As a first step toward the goal of simultaneous uranium and plutonium isotope ratio determinations, the initial characterization and optimization of the platform for the detection of plutonium are reported. Collision-induced dissociation modality settings were optimized to reduce water-related and other molecular clusters containing plutonium, maximizing 242Pu16O2+ responses. A design of experiments study was conducted to optimize the discharge conditions of the dual-electrode LS-APGD toward the responsivity of 242Pu16O2+. The measurement sensitivity was determined from a Pu response curve, yielding a limit of detection of 10 fg (absolute) of total analyte when data was collected and processed with a Spectroswiss FTMS Booster X2 data acquisition system. Additionally, plutonium and uranium were measured in a simultaneous acquisition, and each analyte remained unaffected by the other. It is believed that the LS-APGD-Orbitrap platform could be a valuable addition to the nuclear forensics' toolbox and, indeed, other scientific disciplines and regulatory communities in which rapid, high-resolution plutonium determinations are paramount.

Towards Automated and High-Throughput Quantitative Sizing and Isotopic Analysis of Nanoparticles via Single Particle-ICP-TOF-MS.

The work described herein assesses the ability to characterize gold nanoparticles (Au NPs) of 50 and 100 nm, as well as 60 nm silver shelled gold core nanospheres (Au/Ag NPs), for their mass, respective size, and isotopic composition in an automated and unattended fashion. Here, an innovative autosampler was employed to mix and transport the blanks, standards, and samples into a high-efficiency single particle (SP) introduction system for subsequent analysis by inductively coupled plasma-time of flight-mass spectrometry (ICP-TOF-MS). Optimized NP transport efficiency into the ICP-TOF-MS was determined to be >80%. This combination, SP-ICP-TOF-MS, allowed for high-throughput sample analysis. Specifically, 50 total samples (including blanks/standards) were analyzed over 8 h, to provide an accurate characterization of the NPs. This methodology was implemented over the course of 5 days to assess its long-term reproducibility. Impressively, the in-run and day-to-day variation of sample transport is assessed to be 3.54 and 9.52% relative standard deviation (%RSD), respectively. The determination of Au NP size and concentration was of <5% relative difference from the certified values over these time periods. Isotopic characterization of the 107Ag/109Ag particles (n = 132,630) over the course of the measurements was determined to be 1.0788 ± 0.0030 with high accuracy (0.23% relative difference) when compared to the multi-collector-ICP-MS determination.

Analysis of solid uranium particulates on cotton swipes with an automated microextraction-ICP-MS system.

An automated microextraction method coupled to an inductively coupled plasma - mass spectrometer (ICP-MS) was developed for the direct analysis of solid uranium particulates on the surface of cotton swipes. The microextraction probe extracts particulates from the sample surface, in a flowing solvent, and directs the removed analyte to an ICP-MS for isotopic determination. The automated system utilizes a mechanical XY stage that is software controlled with the capability of saving and returning to specific locations and a camera focused to the swipe surface for optimal viewing of the extracted locations (i.e., material present). Here, particulates (n = 135) were extracted and measured by ICP-MS, including 35 depleted uranyl nitrate hexahydrate (UN) (used for mass bias corrections), 50 uranyl fluoride (UO2F2), and 50 uranyl acetate (UAc) particulates. Blank extractions were performed on the cotton swipes between triplicate sample analyses. Between each swipe extraction, the probe was sent between two wells containing 10% and 5% HNO3 to clean the probe head and to eliminate any analyte carryover between particulates. The measured 235U/238U and 234U/238U isotope ratios for the UO2F2 particulates were 0.00725(8) and 0.000054(4), a percent relative difference (% RD) of -0.041% and -1.7% from the reference isotope ratios determined in-lab through multi-collector ICP-MS analysis of dissolved aliquots of the U material. The UAc samples had a measured 235U/238U isotope ratio of 0.00206(7), a -0.96% relative difference from the reference value of 0.00208(1). The 234U/238U and 236U/238U isotope ratios were 0.000008(1) and 0.000031(4), -5.1% RD and -4.3% RD, respectively. The automated sample stage enabled seamless and rapid particle analysis, leading to a significant increase in throughput versus what was previously possible. Additionally, the saved location capability reduced user sampling error as sampling locations were easily stored and recalled. Analysis of U particles on the swipe surface - including blanks, mass bias, and triplicate extractions - was completed in less than an hour without any sample preparation necessary.

Determination of fluorine distribution in shark teeth by laser-induced breakdown spectroscopy.

Quantifying the chemical composition of fast-growing hard tissues in the environment can shed valuable information in terms of understanding ecosystems both prehistoric and current. Changes in chemical composition can be correlated with environmental conditions and can provide information about the organism's life. Sharks can lose 0.1 to 1.1 teeth/day, depending on species, which offers a unique opportunity to record environmental changes over a short duration of time. Shark teeth contain a biomineral phase that is made up of fluorapatite [Ca5(PO4)3F], and the F distribution within the tooth can be correlated to tooth hardness. Typically, this is determined by bulk acid digestion, energy-dispersive X-ray spectroscopy (EDS), or wavelength-dispersive spectroscopy. Here we present laser-induced breakdown spectroscopy (LIBS) as an alternative and faster approach for determining F distribution within shark teeth. Using a two-volume laser ablation chamber (TwoVol3) with innovative embedded collection optics for LIBS, shark teeth were investigated from sand tiger (Carcharias Taurus), tiger (Galeocerdo Cuvier), and hammerhead sharks (Sphyrnidae). Fluorine distribution was mapped using the CaF 603 nm band (CaF, Β 2Σ+ → X 2Σ+) and quantified using apatite reference materials. In addition, F measurements were cross referenced with EDS analyses to validate the findings. Distributions of F (603 nm), Na (589 nm), and H (656 nm) within the tooth correlate well with the expected biomineral composition and expected tooth hardness. This rapid methodology could transform the current means of determining F distribution, particularly when large sample specimens (350 mm2, presented here) and large quantities of specimens are of interest.

Direct isotopic analysis of solid uranium particulates on cotton swipes by microextraction-ICP-MS.

Direct isotope ratio analysis of solid uranium particulates on cotton swipes was achieved using a solution-based microextraction technique, coupled to a quadrupole inductively coupled plasma - mass spectrometer (ICP-MS). This microextraction-ICP-MS methodology provides rapid isotopic analysis which could be applicable to nuclear safeguards measurements. Particulates of uranyl nitrate hexahydrate (UO2(NO3)2·6H2O) and uranyl fluoride (UO2F2) ranging from 6 µm to 40 µm in length were transferred to cotton swipes with a particle manipulator. The microextraction probe then delivers a 5% nitric acid (HNO3) solvent onto the swipe surface to extract the uranium species. The extracted sample is then delivered to the ICP-MS for isotopic determination. The majority of uranium signal (∼99% and ∼94% for UO2(NO3)2·6H2O and UO2F2, respectively) was detected in the first 15 s extraction, while subsequent extractions on the same location had low or no U signal, suggesting near complete removal of the solid uranium compounds from the swipe surface. Ten samples (for each of the uranium compounds), were analyzed for their isotopic composition. For UO2(NO3)2·6H2O, the determined isotope ratios resulted in a % relative difference (% RD) from the referenced isotope ratios of 0.97, 1.0, and 7.3% for 234U/238U, 235U/238U, and 236U/238U, respectively. The % RD of the UO2F2 isotope ratios were 1.9 and 0.60% for 234U/238U and 235U/238U, respectively. The preliminary limits of detection were determined to be 0.002, 0.4, and 60 pg for 234U, 235U and 238U, respectively This work demonstrates that microextraction ICP-MS is a rapid and sensitive method that could directly determine uranium isotope ratios of UO2(NO3)2·6H2O and UO2F2 particulates on cotton swipes.

Direct Uranium Isotopic Analysis of Swipe Surfaces by Microextraction-ICP-MS.

The ability to directly measure uranium isotope ratios on environmental swipes has been achieved through a solution-based microextraction process and represents a significant advancement toward the development of a rapid method to analyze international nuclear safeguard samples. Here, a microextraction probe is lowered and sealed onto the swipe surface, and analytes within the sampling site (∼8 mm2) are dissolved and extracted into a flowing solvent of 2% nitric acid (HNO3). The mobilized species are subsequently directed into an inductively coupled plasma-mass spectrometer (ICP-MS) for accurate and precise isotope ratio determination. This work highlights the novelty of the sampling mechanism, particularly with the direct coupling of the microextraction probe to the ICP-MS and measurement of uranium isotope ratios. The preliminary method detection limit for the microextraction-ICP-MS method, utilizing a quadrupole-based MS, was determined to be ∼50 pg of 238U. Additionally, precise and accurate isotope ratio measurements were achieved on uranium reference materials for both the major (235U/238U) and minor (234U/238U and 236U/238U) ratios. While the present work is focused on directly measuring uranium isotopic systems on swipe surfaces for nuclear safeguards and verification applications, the benefits would extend across many applications in which direct solid sampling is sought for elemental and isotopic analysis.

Determination of phosphorus and sulfur in uranium ore concentrates by triple quadrupole inductively coupled plasma mass spectrometry.

The analysis of impurities in a uranium ore concentrate (UOC) could provide information regarding the source, production history, and potential intended use of the UOC. This study involves the analysis of UOC samples for phosphorus and sulfur. Concentrations were determined by triple quadrupole inductively coupled plasma - mass spectrometry and compared with results from a pyrohydrolysis method as well as previously reported results. The sulfur and phosphorus concentrations, determined by the mass spectrometer, were used to explore possible trends in a series of UOC material, and the uncertainties were calculated using GUM workbench software. The triple quadrupole inductively coupled plasma - mass spectrometer method allows for the removal of interferences in the analysis of species.

Trace Elemental Analysis of Bulk Thorium Using an Automated Separation-Inductively Coupled Plasma Optical Emission Spectroscopy Methodology.

Presented here is a novel automated method for determining the trace element composition of bulk thorium by inductively coupled plasma-optical emission spectroscopy (ICP-OES). ICP-OES is a universal approach for measuring the trace elemental impurities present in actinide-rich materials; however, due to the emission rich spectrum of the actinide, a separation from the trace elements is warranted for spectrochemical analysis. Here, AG MP-1 ion exchange resin was utilized for retention of the Th matrix, while allowing the trace element impurities to be separated prior to subsequent analysis using ICP-OES. After demonstrating the separation on traditional gravity-driven columns, the methodology was transitioned to an automated platform for comparison. This automated platform utilizes syringe-driven sample and solvent flow and can collect the trace element and thorium fractions in separate locations. While reducing the sample size (500 µL, 1.5 mg of Th), maintaining the overall separation efficiency (recoveries >95%), and illustrating the sample throughput ability (n = 10+), this automated methodology could be readily adopted to nuclear facilities in which the determination of trace elemental impurities in Th samples is warranted.

Rapid Determination of Uranium Isotopic Abundance from Cotton Swipes: Direct Extraction via a Planar Surface Reader and Coupling to a Microplasma Ionization Source.

The collection of solid particulates and liquids from surfaces by the use of cloth swipes is fairly ubiquitous. In such methods, there is a continuous concern regarding the ability to locate and quantitatively sample the analyte species from the material. In this effort, we demonstrate the initial coupling of an Advion Plate Express plate reader to a liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma ionization source with an Orbitrap mass spectrometer to perform uranium isotopic analyses of solution residues on cotton swipes. The Plate Express employs a sampling probe head to engage and seal against the swipe surface. Subsequentially, the analyte residues are desorbed and transported within a 2% HNO3 electrolyte flow to the ionization source. Quantitative recoveries were observed following a single 30 s extraction step, with the absolute mass sampled per extraction being ∼100 ng. While the intrasample variability in the analytical responses for triplicate sampling of the same swipe yield ∼30% RSD, this lack of precision is offset by the ability to determine isotope ratios for enriched uranium specimens with a precision of better than 10% RSD. Pooled, intersample precision (n = 9) was found to be <5%RSD across the various sample compositions. Finally, 235U/238U determinations (ranging from 0.053 to 1.806) were accurate with errors of <10%, absolute. The 234U- and 236U-inclusive ratios were determined with similar accuracy in enriched samples. While the driving force for the effort is in the realm of nuclear nonproliferation efforts, the ubiquitous use of cloth swipes across many application areas could benefit from this convenient approach, including the use of versatile, reduced-format mass spectrometer systems.

Revealing 3D Morphological and Chemical Evolution Mechanisms of Metals in Molten Salt by Multimodal Microscopy.

Growing interest in molten salts as effective high-temperature heat-transfer fluids for sustainable energy systems drives a critical need to fundamentally understand the interactions between metals and molten salts. This work utilizes the multimodal microscopy methods of synchrotron X-ray nanotomography and electron microscopy to investigate the 3D morphological and chemical evolution of two-model systems, pure nickel metal and Ni-20Cr binary alloy, in a representative molten salt (KCl-MgCl2 50-50 mol %, 800 °C). In both systems, unexpected shell-like structures formed because of the presence of more noble tungsten, suggesting a potential route of using Ni-W alloys for enhanced molten-salt corrosion resistance. The binary alloy Ni-20Cr developed a bicontinuous porous structure, reassembling functional porous metals manufactured by dealloying. This work elucidates better mechanistic understanding of corrosion in molten salts, which can contribute to the design of more reliable alloys for molten salt applications including next-generation nuclear and solar power plants and opens the possibility of using molten salts to fabricate functional porous materials.

Optimization of uranium and plutonium separations using TEVA and UTEVA cartridges for MC-ICP-MS analysis of environmental swipe samples.

The analysis of environmental swipe samples for ultra-trace uranium (U) and plutonium (Pu) determinations is essential in the nuclear safeguards community. While mass spectrometry techniques for U and Pu detection continually improve, established separation methods are seldom reevaluated. Currently, actinide separations within the forensics community predominantly employ either Eichrom TEVA® or UTEVA® resins. The direct optimization of U and Pu separations utilizing both resins has not been widely reported. Here, several methods were explored with goals of increasing analyte recovery, acquiring cleaner blanks, and improving the separation efficiency of ultra-trace levels of U and Pu from environmental swipe samples. The optimized separation methodology of U and Pu was examined using certified reference materials and archived environmental swipe samples.

Evaluation and Specifications for In-Line Uranium Separations Using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) Detection for Trace Elemental Analysis.

Automated introduction platforms integrated with inductively coupled plasma optical emission spectroscopy (ICP-OES) systems are continuously being improved. Expanding on the introduction systems, a newly developed automated ion chromatography system was explored for performing rapid in-line separations coupled to ICP-OES for the detection of trace elements in uranium. Trace elements are separated from a uranium material and the analytes are directed into the ICP-OES for subsequent detection. Detection parameters such as exposure time frequency, wavelength selection, and settling times were explored to gain insight on optimal detection schemes for in-line trace elemental analysis. The methodology was applied in the analysis of a uranium oxide (U3O8) certified reference material, CRM-124. It was found here that the sensitivity and uncertainty of the technique are greatly affected by how the ICP-OES is employed to collect data. Overall it was determined that faster exposure replicates can provide greater peak resolution with higher fidelity measurements but are limited with respect to the total analysis time (i.e., limited in detection timely separations). Zeta scores, which combine accuracy and uncertainty of certified values and experimental values, were used to validate the ICP-OES modes of operation.

Initial Benchmarking of the Liquid Sampling-Atmospheric Pressure Glow Discharge-Orbitrap System Against Traditional Atomic Mass Spectrometry Techniques for Nuclear Applications.

The integration of the liquid sampling-atmospheric pressure glow discharge (LS-APGD) ion source with Orbitrap mass spectrometers has resulted in new opportunities in the field of isotope ratio mass spectrometry. In a field that has been dominated by thermal ionization mass spectrometry (TIMS) and inductively coupled plasma mass spectrometry (ICP-MS) on quadrupole and scanning-mode sector field analyzer platforms for highly accurate and precise measurements, the LS-APGD-Orbitrap system offers a benchtop instrument capable of meeting the rigorous International Target Values for measurement uncertainty for uranium (U). In order to benchmark the LS-APGD-Orbitrap, a series of U certified reference materials with increasing 235U isotopic composition were analyzed. By using U samples ranging in enrichment from 1 to 80%, the ability of the system to measure isotope ratios over a wide range is demonstrated. This analysis represents the first time that the LS-APGD-Orbitrap system has been used to analyze highly enriched U samples, allowing for the measurement of each of the U isotopes, including 234U and 236U-related species, which had not been achieved previously. Ultimately, the LS-APGD-Orbitrap system was able to measure CRM U-800 (assayed as 235U / 238U = 4.265622) as 4.266922, with a combined uncertainty, (uc), of 0.040%. These results are compared to those obtained using traditional elemental mass spectrometers including TIMS and ICP-MS-based instruments. The effectiveness of the LS-APGD-Orbitrap MS system for measuring U isotopes shows excellent promise in nuclear forensics, safeguards, and other nuclear weapon-based applications. Graphical Abstract ᅟ.

Trace elemental analysis of bulk uranium materials using an inline automated sample preparation technique for ICP-OES.

An automated inline method for the separation of trace element impurities from uranium matrices using a 200 µL column packed with UTEVA resin is presented here utilizing an Elemental Scientific, Inc. prepFAST IC in combination with a Perkin Elmer Avio 500 ICP-OES. This method reduces human exposure to highly concentrated acids and uranium-rich samples by automating the chemistry and introduction to the ICP. Calibration standards were prepared using inline dilutions requiring a single stock standard. The separation of trace elements from uranium matrices requires samples to be prepared in 8 M HNO3, which can be detrimental to the ICP, thus a post-column dilution step was employed to dilute the eluent matrix to 4 M HNO3. The method was optimized for a sample-to-sample time of < 9 min and monitored 21 elements in total. Proof of concept experiments for 1 µg mL-1 trace elements spiked into 0.1 vol%, 0.5 vol%, and 1.0 vol% uranium matrices resulted in < 5% relative difference and < 10% relative standard deviation for triplicate measurements of each uranium matrix analyzed. Inline dilutions (pre-column) of 2 vol% uranium + 20 µg mL-1 trace elements resulted in accurate and precise measurements using dilution factors of 2×, 4×, 5×, and 20×. Method detection limits for the 21 elements (Al, B, Ba, Be, Cd, Ca, Co, Cu, Fe, Li, Pb, Mg, Mn, Ni, K, Sr, Na, V, Zn, Zr, and U) analyzed for ranged from 7 to 326 ng mL-1 for 70 µL volume injections.

An automated micro-separation system for the chromatographic removal of uranium matrix for trace element analysis by ICP-OES.

An automated, miniaturized, off-line separation technique is presented here using an Elemental Scientific Inc. microFAST MC system with UTEVA resin to extract the uranium matrix from its trace element impurities in aqueous media. The collected fractions were analyzed for ~ 30 trace elements using inductively coupled plasma - optical emission spectroscopy. Ten replicate samples were processed with a single column resulting in precision ranging from 3.3% to 6.2% relative standard deviation with regards to the trace element recoveries. Accuracy, with respect to trace element concentrations in the U3O8 Certified Reference Material 124-1, resulted in an average of 13.9% relative deviation while accuracy to the Canadian U3O8 reference material, CUP-2, resulted in an average relative deviation of 8.6%. The total separation time of this automated process was reduced to ~ 30 min per sample while employing a 0.5 mL UTEVA chromatographic resin bed and 2.5 mg of uranium.