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Title: Mass Spectrometric Determination of Uranium and Thorium in High Radiopurity Polymers Using Ultra Low Background Electroformed Copper Crucibles for Dry Ashing

Abstract

A rapid new method for determining the U and Th mass concentrations in high radiopurity plastics is described, consisting of 1) dry ashing the plastic sample and tracers in low mass crucibles made of ultra low background electroformed copper (ULB EF-Cu) foil cut and folded into boats, 2) dissolving both the ash and the boat in acid, 3) performing a column separation to remove copper, and 4) determining the elements of interest by isotope dilution mass spectrometry. This method was demonstrated on both unfluorinated and fluorinated plastics, demonstrating high tracer recoveries and detection limits to pg/g (i.e., parts per trillion) levels or below, corresponding to μBq/kg of material. Samples of biomedical polyester (Max-Prene® 955) and a fluoropolymer (polyvinylidene fluoride, PVDF) were analyzed in powder raw material forms as well as solids in the form of pellets or injection molded parts. The polyester powder contained 6 pg/g and 2 pg/g for Th and U respectively. These levels correspond to 25 and 25 μBq/kg radioactivity, respectively. Determinations on samples of PVDF powder were typically below 1 pg/g for Th and 2 pg/g for U, corresponding to 4 and 25 μBq/kg radioactivity, respectively. The use of low mass ULB EF-Cu boats for drymore » ashing successfully overcame the problem of crucible-generated contaminants in the analysis; absolute detection limits, calculated as 3 × standard deviation of the process blanks, were typically 20-100 fg within a sample set. Complete dissolution of the ash and low mass boat provided high tracer recoveries, and provides a convincing method to recover both the tracer and sample isotopes when full equilibration of tracer isotopes with sample isotopes is not possible prior to beginning chemical sample processing on solids.« less

Authors:
; ; ; ORCiD logo
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1353306
Report Number(s):
PNNL-SA-122983
Journal ID: ISSN 0003-2700
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Analytical Chemistry; Journal Volume: 89; Journal Issue: 5
Country of Publication:
United States
Language:
English
Subject:
polymer; EFCu Electroformed copper; ICP-MS; Uranium; rare event physics; ultra low background materials

Citation Formats

Arnquist, Isaac J., Hoppe, Eric J., Bliss, Mary, and Grate, Jay W. Mass Spectrometric Determination of Uranium and Thorium in High Radiopurity Polymers Using Ultra Low Background Electroformed Copper Crucibles for Dry Ashing. United States: N. p., 2017. Web. doi:10.1021/acs.analchem.6b04854.
Arnquist, Isaac J., Hoppe, Eric J., Bliss, Mary, & Grate, Jay W. Mass Spectrometric Determination of Uranium and Thorium in High Radiopurity Polymers Using Ultra Low Background Electroformed Copper Crucibles for Dry Ashing. United States. doi:10.1021/acs.analchem.6b04854.
Arnquist, Isaac J., Hoppe, Eric J., Bliss, Mary, and Grate, Jay W. Tue . "Mass Spectrometric Determination of Uranium and Thorium in High Radiopurity Polymers Using Ultra Low Background Electroformed Copper Crucibles for Dry Ashing". United States. doi:10.1021/acs.analchem.6b04854.
@article{osti_1353306,
title = {Mass Spectrometric Determination of Uranium and Thorium in High Radiopurity Polymers Using Ultra Low Background Electroformed Copper Crucibles for Dry Ashing},
author = {Arnquist, Isaac J. and Hoppe, Eric J. and Bliss, Mary and Grate, Jay W.},
abstractNote = {A rapid new method for determining the U and Th mass concentrations in high radiopurity plastics is described, consisting of 1) dry ashing the plastic sample and tracers in low mass crucibles made of ultra low background electroformed copper (ULB EF-Cu) foil cut and folded into boats, 2) dissolving both the ash and the boat in acid, 3) performing a column separation to remove copper, and 4) determining the elements of interest by isotope dilution mass spectrometry. This method was demonstrated on both unfluorinated and fluorinated plastics, demonstrating high tracer recoveries and detection limits to pg/g (i.e., parts per trillion) levels or below, corresponding to μBq/kg of material. Samples of biomedical polyester (Max-Prene® 955) and a fluoropolymer (polyvinylidene fluoride, PVDF) were analyzed in powder raw material forms as well as solids in the form of pellets or injection molded parts. The polyester powder contained 6 pg/g and 2 pg/g for Th and U respectively. These levels correspond to 25 and 25 μBq/kg radioactivity, respectively. Determinations on samples of PVDF powder were typically below 1 pg/g for Th and 2 pg/g for U, corresponding to 4 and 25 μBq/kg radioactivity, respectively. The use of low mass ULB EF-Cu boats for dry ashing successfully overcame the problem of crucible-generated contaminants in the analysis; absolute detection limits, calculated as 3 × standard deviation of the process blanks, were typically 20-100 fg within a sample set. Complete dissolution of the ash and low mass boat provided high tracer recoveries, and provides a convincing method to recover both the tracer and sample isotopes when full equilibration of tracer isotopes with sample isotopes is not possible prior to beginning chemical sample processing on solids.},
doi = {10.1021/acs.analchem.6b04854},
journal = {Analytical Chemistry},
number = 5,
volume = 89,
place = {United States},
year = {Tue Feb 21 00:00:00 EST 2017},
month = {Tue Feb 21 00:00:00 EST 2017}
}