High-Precision Measurement of 186Os/188Os and 187Os/188Os: Isobaric Oxide Corrections with In-Run Measured Oxygen Isotope Ratios

Sample decomposition using inverse aqua regia at elevated temperatures and pressures (e.g., Carius tube or high‐pressure asher) is the most common method used to extract highly siderophile elements (HSEs: Ru, Rh, Pd, Re, Os, Ir, Pt and Au) from geological samples. Recently, it has been recognised that additional HF desilicification is necessary to better recover HSEs, potentially contained within silicate or oxide minerals in mafic samples, which cannot be dissolved solely by inverse aqua regia. However, the abundance of interfering elements tends to increase in the eluent when conventional ion‐exchange purification procedures are applied to desilicified samples. In this study, we developed an improved purification method to determine HSEs in desilicified samples. This method enables the reduction of the ratios of isobaric and polyatomic interferences, relative to the measured intensities of HSE isotope masses, to less than a few hundred parts per million. Furthermore, the total procedural blanks are either comparable to or lower than conventional methods. Thus, this method allows accurate and precise HSE measurements in mafic and ultramafic geological samples, without the need for interference corrections. Moreover, the problem of increased interfering elements, such as Zr for Pd and Cr for Ru, is circumvented for the desilicified samples.

Section: Methodssupporting

confidence: 93%

A Method to Suppress Isobaric and Polyatomic Interferences for Measurements of Highly Siderophile Elements in Desilicified Geological Samples

Zhou

Tanaka

Yamanaka

et al. 2019

“…), 0.160920 ± 12 (Chu et al . ) and 0.160922 ± 3 (Chatterjee and Lassiter ) using 10 11 Ω amplifiers and

^{192} {OsO}_{3}^{-}

signals of > 1.3 V. Along with the increase in

^{192} {OsO}_{3}^{-}

intensities from 0.02 to 0.35 V, the precision of the 187 Os/ 188 Os ratios significantly improves from 801 to 107 ppm (2 RSD; Figure a). The precision of 107 ppm (2 RSD) at

^{192} {OsO}_{3}^{-}

intensities of 0.20–0.35 V is larger than that of 25 ppm at

^{192} {OsO}_{3}^{-}

intensities of > 1.3 V (Luguet et al .…”

Section: Resultsmentioning

confidence: 96%

High‐Precision Measurement of ¹⁸⁷Os/¹⁸⁸Os Isotope Ratios of Nanogram to Picogram Amounts of Os in Geological Samples by N‐TIMS using Faraday Cups Equipped with 10¹³ Ω Amplifiers

Wang

Vollstaedt

2019

N(187Os)/N(188Os) ratios of six geological reference materials were measured using static Faraday cups (FCs) with 1013 Ω amplifiers by N‐TIMS. Our results show that the repeatability precision was 2–3‰ (2 RSD, n = 3), when taking ~ 1 g of BHVO‐2 with 76 pg g−1 of Os mass fraction and ~ 2 g of BCR‐2 with 21 pg g−1 of Os mass fraction for each sample, whether measured by FCs or by secondary electron multiplier. The repeatability precision measured by FCs was 1–0.2‰ (2 RSD, n = 3) when taking ~ 1 g of BIR‐2 with 350 pg g−1 of Os mass fraction, ~ 1 g of WGB‐1 with 493 pg g−1 of Os mass fraction or ~ 0.5 g of WPR‐1 with 13.3 ng g−1 of Os mass fraction for each sample, which is much better than those measured by secondary electron multiplier. Instead, when taking ~ 2 g of AGV‐2 with 4 pg g−1 Os mass fraction, the repeatability precision measured by secondary electron multiplier is 3–4‰ (RSD, n = 3), which is better than those measured by FCs. Of the six reference materials analysed, WPR‐1 and BIR‐1a are the most homogeneous with regard to Os isotopic composition (2 RSD of 0.08% and 0.23%, respectively) when test portion masses are 0.5–1 g.

“…) and Nd (NdO + , DePaolo and Wasserburg ) utilised a uniform O isotopic composition of Nier (): 17 O/ 16 O = 0.000375 and 18 O/ 16 O = 0.002044; more recently, it has been recognised that Nier's O isotopic ratios deviate from the O mass fractionation trend and that O isotopic compositions can vary within individual or across multiple measurements (e.g., in the Os (

{OsO}_{3}^{-}

) isotopic measurements, Walker , Chatterjee and Lassiter , Chu et al . ). In order to overcome these issues, it is now recommended to use line by line measured O isotopic ratios by measuring, x M 16

O_{3}^{-}

x−1 M 16 O 2 17 O − and x−2 M 16 O 2 18 O − on Faraday cups mounted with high feedback 10 12 Ω or 10 13 Ω resistor current amplifiers (Chu et al .…”

Section: Advances In Thermal Ionisation Mass Spectrometrymentioning

confidence: 97%

“… , Touboul and Walker , Liu and Pearson , Chatterjee and Lassiter , Chu et al . , Bermingham et al . , Nagai and Yokoyama , Worsham et al .…”

Section: Advances In Thermal Ionisation Mass Spectrometrymentioning

confidence: 99%

“…In order to overcome these issues, it is now recommended to use line by line measured O isotopic ratios by measuring, x M 16

O_{3}^{-}

x−1 M 16 O 2 17 O − and x−2 M 16 O 2 18 O − on Faraday cups mounted with high feedback 10 12 Ω or 10 13 Ω resistor current amplifiers (Chu et al . , Bermingham et al . , Trinquier et al .…”

Section: Advances In Thermal Ionisation Mass Spectrometrymentioning

confidence: 99%

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GGR Biennial Critical Review: Analytical Developments Since 2014

Linge

Bèdard

Bugoi

et al. 2017

This GGR biennial critical review covers developments and innovations in key analytical methods published since January 2014, relevant to the chemical, isotopic and crystallographic characterisation of geological and environmental materials. In nine selected analytical fields, publications considered to be of wide significance are summarised, background information is provided and their importance evaluated. In addition to instrumental technologies, this review also presents a summary of new developments in the preparation and characterisation of rock, microanalytical and isotopic reference materials, including a précis of recent changes and revisions to ISO guidelines for reference material characterisation and reporting. Selected reports are provided of isotope ratio analyses by both solution-nebulisation MC-ICP-MS and laser ablation-ICP-MS, as well as of radioactive isotope geochronology by LA-ICP-MS. Most of the analytical techniques elaborated continue to provide new applications for geochemical analysis, however it is noted that instrumental neutron activation analysis has become less popular in recent years, mostly due to the reduced availability of nuclear reactors to act as a neutron source. Many of the newer applications reported here provide analysis at increasingly finer resolution. Examples include atom probe tomography, a very sensitive method providing atomic scale information, nanoscale SIMS, for isotopic imaging of geological and biological samples, and micro-XRF, which has a spatial resolution many orders of magnitude smaller than conventional XRF