Jason Day

Determination of multiple element/calcium ratios in foraminiferal calcite by quadrupole ICP-MS

A method has been developed for rapid and precise simultaneous determination of nine element/Ca ratios in foraminiferal tests directly from intensity ratios using external, matrix-matched standards on a quadrupole inductively coupled plasma–mass spectrometer (ICP-MS). All quantification isotopes are determined in pulse mode to avoid cross-calibration. Small argide (40Ar26Mg) interferences on 66Zn are corrected by using two additional Mg and Zn standards. A stable signal, conducive for high-precision measurements, is obtained by cone conditioning. Variable calcium concentration has negligible effect on Li, Al, Mn, and Sr, but Ca concentrations for standards and samples need to be constrained at a similar level for precise measurements of Zn, Cd, and U. Aliquots of samples are first analyzed for Ca concentrations on an inductively coupled plasma–atomic emission spectrometer (ICP-AES), and the remaining solutions are diluted to Ca concentration of 100 ppm for ratio measurements to assure data quality. The long-term reproducibility of the method yielded precisions of Li/Ca = 2.4%, B/Ca = 4.2%, Mg/Ca = 1.4%, Al/Ca = 14%, Mn/Ca = 0.9%, Zn/Ca = 2.8% (1.2∼7.8 μmol/mol) and 5.1% (0.5∼1.2 μmol/mol), Sr/Ca = 0.9%, Cd/Ca = 2.4% (0.07∼0.24 μmol/mol) and 4.8% (0.01∼0.07 μmol/mol), and U/Ca = 2.5% for foraminiferal samples as small as 60 μg.

Preferential dissolution of benthic foraminiferal calcite during laboratory reductive cleaning

We have investigated the effect of cleaning procedures on eight element/Ca ratios in three widely used benthic foraminifera species from core top and down core sediments. Two cleaning techniques were employed: (1) comparison between “Mg-cleaning” and “Cd-cleaning” methods and (2) comparison between the various constituent reagents. Li/Ca, B/Ca, and Sr/Ca ratios remained unchanged for samples subjected to different treatments, but Mg/Ca, Mn/Ca, Zn/Ca, Cd/Ca, and U/Ca were substantially decreased when foraminifera shells were cleaned with reagents containing citrate. In contrast, no significant decreases in element/Ca ratios were observed for samples cleaned in N2H4 without citrate, indicating that the role of N2H4 was insignificant during reductive cleaning and that citrate is responsible for decreases of Mg/Ca, Mn/Ca, Zn/Ca, Cd/Ca, and U/Ca. Decreases in these ratios are most likely due to (1) removal of contaminant particles enriched in Mg, Mn, Zn, Cd and U and/or (2) preferential leaching of CaCO3 by the formation of stable metal complexes through chelation between citrate and metals heterogeneously distributed in foraminiferal shells. Due to the negligible effect of N2H4 and preferential dissolution of CaCO3 during reductive cleaning, it is suggested that the reductive cleaning step should be omitted and the “Mg-cleaning” method [Barker et al., 2003] could be employed to clean foraminiferal shells for trace element measurements.

Atomic Spectrometry Update. Advances in atomic spectrometry and related techniques

This is the second iteration of this review covering developments in ‘Atomic Spectrometry’. It covers atomic emission, absorption, fluorescence and mass spectrometry, but excludes material on speciation and coupled techniques which is included in a separate review. It should be read in conjunction with the other related reviews in the series.1-5 A critical approach to the selection of material has been adopted, with only novel developments in instrumentation, techniques and methodology being included. The major growth areas in evidence were the use of MC-ICP-MS as the method of choice for isotope ratio analyses, and new applications of AMS. The decline in the number of fundamental studies and developments in chemometrics continued. Some novel instrumental methods, such as the portable liquid electrode plasma, were reported and there were many new applications of solid phase extractants for on-line sample pretreatment, particularly using carbon nanotubes.

Advances in atomic spectrometry and related techniques

This is the second iteration of this review covering developments in ‘Atomic Spectrometry’. It covers atomic emission, absorption, fluorescence and mass spectrometry, but excludes material on speciation and coupled techniques which is included in a separate review.1 It should be read in conjunction with the other related reviews in the series.2–5 A critical approach to the selection of material has been adopted, with only novel developments in instrumentation, techniques and methodology being included. Most techniques have reached a level of maturity which precludes the emergence of ‘stand-out’ new developments. It is noteworthy that there are very few novel publications in sections on chemometrics, fundamental studies, or direct solids analysis. Sample introduction continues to generate a steady stream of research outputs, but these are mainly derivative and focused on applications. The advent of SF-ICP-MS is becoming widely adopted as a reliable technique for IR measurements, so this had been the main growth area. Likewise, the use of femtosecond UV lasers has now entered the mainstream for geological applications.

High precision measurement of germanium isotope ratio variations by multiple collector-inductively coupled plasma mass spectrometry

Multicollector ICP-MS is used for the precise measurement of variations in the isotopic composition of germanium. Argon-based spectral interferences are assessed in the germanium mass region and the repeatability of the following ratios is determined: 74Ge/70Ge, 73Ge/70Ge and 72Ge/70Ge. The isotope ratio repeatability of a mono-elemental solution relative to another mono-elemental solution is better than 0.06‰ per u at 95% confidence. Variations in sample 74Ge/70Ge, 73Ge/70Ge, and 72Ge/70Ge ratios are expressed as δ74Ge δ73Ge and δ72Ge units, respectively, which are deviations in parts per 103 from the same ratio in the standard solution. The addition of sodium and potassium to a standard solution of germanium having a known isotopic composition induces up to 4.4‰ decrease of δ74Ge. This chemical bias is a result of a mass-dependent process and prevents the measurement of natural samples without chemical separation. Germanium is quantitatively separated from alkali matrix using liquid chromatography techniques.

Research data supporting the publication: 'The effect of fission-energy Xe ion irradiation on the structural integrity and dissolution of the CeO

Project: PhD work by A.J. Popel: ‘The effect of radiation damage by fission fragments on the structural stability and dissolution of the UO2 fuel matrix’. The Excel file ‘XRD_CeO2’ with raw XRD data supporting the CeO2 powder XRD results The Text files ‘sample1_wt’ and ‘sample2_wt’ with raw EPMA data supporting the EPMA analysis of the two bulk CeO2 samples The Excel file ‘ICP-MS data’ with output ICP-MS data and calculations for water and acid dilutions supporting Figures 5 and 6 and ICP-MS results in the publication: A.J. Popel, S. Le Solliec, G.I. Lampronti, J. Day, P.K. Petrov, I. Farnan, The effect of fission-energy Xe ion irradiation on the structural integrity and dissolution of the CeO2 matrix, J. Nucl. Mater. 484 (2017) 332-338, https://doi.org/10.1016/j.jnucmat.2016.10.046. The XRD analysis was performed to verify the identity of the as-supplied bulk samples and check for other phases. The data were generated on the 5th of June 2014 at the Department of Earth Sciences, University of Cambridge, Cambridge, UK. A bulk sample of the as-supplied CeO2 was powdered using mortar and pestle and analysed on a D8 Bruker diffractometer equipped with a primary Ge monochromator for Cu Ka1 and a Sol-X solid state detector operating in standard Bragg-Brentano geometry. The sample was spun during signal collection and a zero-background sample holder was used. The EPMA analysis was performed to check the composition of the as-supplied bulk samples. The data were generated on the 3rd of July 2014 at the Department of Earth Sciences, University of Cambridge, Cambridge, UK. Prior to the analysis, the samples were embedded in a resin, polished and carbon coated to ensure conductivity for the analysis using a Cameca SX-100 electron microprobe analyser. Calibration of the equipment was performed using a set of rare earth elements. The ICP-MS analysis was performed to measure 140Ce concentration in the extracted solutions. The data were generated on the 23rd of July 2014 at the Department of Earth Sciences, University of Cambridge, Cambridge, UK, on a Perkin Elmer SCIEX Elan DRC II quadrupole ICP-MS. The data can be accessed through the University of Cambridge Data Repository.

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Project: PhD work by A.J. Popel: ‘The effect of radiation damage by fission fragments on the structural stability and dissolution of the UO2 fuel matrix’. The Excel file ‘U_ICP-MS data’ with output ICP-MS data and calculations for water and acid dilutions supporting Figures 2 and 3 and ICP-MS results in the publication: A.J. Popel, V.G. Petrov, V.A. Lebedev, J. Day, S.N. Kalmykov, R. Springell, T.B. Scott, I. Farnan, The effect of fission-energy Xe ion irradiation on dissolution of UO2 thin films, J. Alloys Compd. 721 (2017) 586-592, https://doi.org/10.1016/j.jallcom.2017.05.084. The ICP-MS analysis was performed to measure 238U concentration in the extracted solutions. The data were generated on the 13-14th of October 2014 at the Department of Earth Sciences, University of Cambridge, Cambridge, UK, on a Perkin Elmer SCIEX Elan DRC II quadrupole ICP-MS. The data can be accessed through the University of Cambridge Data Repository.