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High-Precision Measurement of Eu/Eu* in Geological Glasses via LA-ICP-MS AnalysisElemental fractionation during laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis has been historically documented between refractory and volatile elements. In this work, however, we observed fractionation between light rare earth elements (LREEs) and heavy rare earth elements (HREEs) when using ablation strategies involving large spot sizes (greater than 100 millimeters) and line scanning mode. In addition: (1) ion yields decrease when using spot sizes above 100 millimeters; (2) (Eu/Eu*)(sub raw) (i.e. Europium anomaly) positively correlates with carrier gas (He) flow rate, which provides control over the particle size distribution of the aerosol reaching the ICP; (3) (Eu/Eu*)(sub raw) shows a positive correlation with spot size, and (4) the changes in REE signal intensity, induced by the He flow rate change, roughly correlate with REE condensation temperatures. The REE fractionation is likely driven by the slight but significant difference in their condensation temperatures. Large particles may not be completely dissociated in the ICP and result in preferential evaporation of the less refractory LREEs and thus non-stoichiometric particle-ion conversion. This mechanism may also be responsible for Sm-Eu-Gd fractionation as Eu is less refractory than Sm and Gd. The extent of fractionation depends upon the particle size distribution of the aerosol, which in turn is influenced by the laser parameters and matrix. Ablation pits and lines defined by low aspect ratios produce a higher proportion of large particles than high aspect ratio ablation, as confirmed by measurements of particle size distribution in the laser induced aerosol. Therefore, low aspect ratio ablation introduces particles that cannot be decomposed and/or atomized by the ICP and thus results in exacerbated elemental fractionation. Accurate quantification of REE concentrations and Eu/Eu* requires reduction of large particle production during laser ablation. For the reference materials analyzed in this work, the 100 millimeters spot measurements of Eu/Eu* agreed with GeoRem preferred values within 3 percent. Our long-term analyses of Eu/Eu* in MPI-DING glass KL-2G and USGS glass BIR-1G were reproducible at 3 percent (2 RSD).
Document ID
20160005751
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Tang, Ming
(Maryland Univ. College Park, MD, United States)
McDonough, William F.
(Maryland Univ. College Park, MD, United States)
Arevalo, Ricardo, Jr.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
May 3, 2016
Publication Date
July 1, 2014
Publication Information
Publication: Journal of Analytical Atomic Spectrometry
Publisher: The Royal Society of Chemistry
Volume: 29
Issue: 10
e-ISSN: 1364-5544
Subject Category
Metals And Metallic Materials
Instrumentation And Photography
Chemistry And Materials (General)
Report/Patent Number
GSFC-E-DAA-TN21399
Funding Number(s)
CONTRACT_GRANT: NSF-EAR-0739006
Distribution Limits
Public
Copyright
Other
Keywords
geological glasses
LA-ICP-MS analysis
measurement - mass spectrometry

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