9 research outputs found
Investigation of the 176Yb Interference Correction during Determination of the 176Hf/177Hf Ratio by Laser Ablation and Solution Analysis on the Neoma MC-ICP-MS
We utilized the Neoma™, a recently released MC-ICP-MS platform offered by ThermoFisher Scientific, to assess the behavior of the Lu-Yb-Hf system during laser ablation analyses of various zircon standards as well as solution-based analyses of the JMC-475 Hf standard doped with varying quantities of Yb and Lu. The primary goal of this work was to characterize the behavior of the Yb interference correction on the Neoma™ platform since this is one of the biggest issues in the Hf isotope analysis community and because the Neoma™ platform will supplant the Neptune™ series instrument. During laser ablation analysis, we found that the overall data quality scales proportionally with the total Hf signal intensity, with higher signal analyses producing extremely accurate (within 1 εHf unit) and precise (sub εHf unit within-run standard errors) data. At low Yb signals (<0.1 V 173Yb), we were not able to produce an accurate internal Yb mass bias factor. However, utilizing an empirical approach allows for the application of session-specific relationships between the Yb and Hf mass bias factors, determined by analysis of standards of varying Yb content, to produce accurate εHf values from zircons with higher Yb/Hf ratios even where the total Hf signal intensity is relatively low. Similar behavior was observed in the solution analyses. Lastly, while the behavior of the Yb interference correction on the Neoma™ platform appears comparable to the Neptune™ series MC-ICP-MS, further work will help refine the understanding of the controls on mass bias behavior, oxide formation, session-to-session stability, etc
Investigation of the <sup>176</sup>Yb Interference Correction during Determination of the <sup>176</sup>Hf/<sup>177</sup>Hf Ratio by Laser Ablation and Solution Analysis on the Neoma MC-ICP-MS
We utilized the Neoma™, a recently released MC-ICP-MS platform offered by ThermoFisher Scientific, to assess the behavior of the Lu-Yb-Hf system during laser ablation analyses of various zircon standards as well as solution-based analyses of the JMC-475 Hf standard doped with varying quantities of Yb and Lu. The primary goal of this work was to characterize the behavior of the Yb interference correction on the Neoma™ platform since this is one of the biggest issues in the Hf isotope analysis community and because the Neoma™ platform will supplant the Neptune™ series instrument. During laser ablation analysis, we found that the overall data quality scales proportionally with the total Hf signal intensity, with higher signal analyses producing extremely accurate (within 1 εHf unit) and precise (sub εHf unit within-run standard errors) data. At low Yb signals (173Yb), we were not able to produce an accurate internal Yb mass bias factor. However, utilizing an empirical approach allows for the application of session-specific relationships between the Yb and Hf mass bias factors, determined by analysis of standards of varying Yb content, to produce accurate εHf values from zircons with higher Yb/Hf ratios even where the total Hf signal intensity is relatively low. Similar behavior was observed in the solution analyses. Lastly, while the behavior of the Yb interference correction on the Neoma™ platform appears comparable to the Neptune™ series MC-ICP-MS, further work will help refine the understanding of the controls on mass bias behavior, oxide formation, session-to-session stability, etc
Rare Earth Element Determination in Uranium Ore Concentrates Using Online and Offline Chromatography Coupled to ICP-MS
The determination of trace elements, particularly rare earth elements, in uranium ore concentrates (UOCs) is important as the pattern can be indictive ore characteristics. Presented here is a methodology for accurately quantifying rare earth elements (REE) in UOCs. To improve the measurement uncertainty, isotope dilution mass spectrometry (IDMS) was utilized over other quantification techniques such as external calibration or standard addition. The isotopic determinations were measured by inductively coupled plasma-mass spectrometry (ICP-MS). To obtain high-fidelity isotopic measurements, separation of the REE from the uranium matrix was achieved by high-performance ion chromatography (HPIC), reducing the isobaric interferences. After separation, the target analytes were analyzed in two different modalities. For high precision analysis, the separated analytes were collected and measured by ICP-MS in an “offline” fashion. For a rapid approach, the separated analytes were sent directly into an ICP-MS for “online” analysis. These methods have been demonstrated to accurately quantify the REE content in a well-characterized UOC sample
Preliminary Assessment of Potential for Metal–Ligand Speciation in Aqueous Solution via the Liquid Sampling–Atmospheric Pressure Glow Discharge (LS-APGD) Ionization Source: Uranyl Acetate
The determination of metals, including
the generation of metal–ligand
speciation information, is essential across a myriad of biochemical,
environmental, and industrial systems. Metal speciation is generally
affected by the combination of some form of chromatographic separation
(reflective of the metal–ligand chemistry) with element-specific
detection for the quantification of the metal composing the chromatographic
eluent. Thus, the identity of the metal–ligand is assigned
by inference. Presented here, the liquid sampling–atmospheric
pressure glow discharge (LS-APGD) is assessed as an ionization source
for metal speciation, with the uranyl ion–acetate system used
as a test system. Molecular mass spectra can be obtained from the
same source by simple modification of the sustaining electrolyte solution.
Specifically, chemical information pertaining to the degree of acetate
complexation of uranyl ion (UO<sub>2</sub><sup>2+</sup>) is assessed
as a function of pH in the spectral abundance of three metallic species:
inorganic (nonligated) uranyl, UO<sub>2</sub>AcÂ(H<sub>2</sub>O)<sub><i>n</i></sub>(MeOH)<sub><i>m</i></sub><sup>+</sup>, and UO<sub>2</sub>Ac<sub>2</sub>(H<sub>2</sub>O)<sub><i>n</i></sub>(MeOH)<sub><i>m</i></sub>H<sup>+</sup> (<i>n</i> = 1, 2, 3, ...; <i>m</i> = 1, 2, 3, ...).
The product mass spectra are different from what are obtained from
electrospray ionization sources that have been applied to this system.
The resulting relationships between the speciation and pH values have
been compared to calculated concentrations of the corresponding uranyl
species: UO<sub>2</sub><sup>2+</sup>, UO<sub>2</sub>Ac<sup>+</sup>, UO<sub>2</sub>Ac<sub>2</sub>. The capacity for the LS-APGD to affect
both atomic mass spectra and structurally significant spectra for
organometallic complexes is a unique and potentially powerful combination
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 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