TY - JOUR
T1 - Evaluation of iodine speciation and 129I/127I ratios at low concentrations in environmental samples using IC-ICP-MS
AU - Kimmig, Sara R.
AU - Thompson, Christopher
AU - Baum, Steven
AU - Brown, Christopher F.
N1 - Funding Information:
This study was funded by the US Department of Energy (DOE) Richland Operations Office. PNNL is operated by Battelle Memorial Institute for the DOE under Contract DE-AC05-6RL01830.
Funding Information:
This research was conducted as part of the Deep Vadose Zone—Applied Field Research Initiative at the Pacific Northwest National Laboratory (PNNL). Funding for this work was provided by the US Department of Energy (DOE) Richland Operations Office. PNNL is operated by Battelle Memorial Institute for the DOE under Contract DE-AC05-6RL01830. We thank Andrew Plymale for help with standard preparation and Michelle Snyder for assistance with sample preparation, Steve Shen for help with the interference corrections, as well as Hilary Emerson, James Szecsody, and Eirik Krogstad for discussions pertaining to iodine in natural samples that led to improvements of this work. Finally, we gratefully acknowledge the anonymous reviewer whose comments helped improve the quality of this manuscript.
Publisher Copyright:
© 2021, Akadémiai Kiadó, Budapest, Hungary.
PY - 2021/2
Y1 - 2021/2
N2 - Subterranean radioiodine contamination at the Hanford Site in Washington State is believed to be present as iodide, iodate, and organo-I species, with iodate being the predominant form. Because these species have different sediment-sorption characteristics, understanding their distribution is important for developing an accurate understanding of iodine migration in the subsurface. Herein, we report a novel, rapid technique for simultaneous iodine speciation (iodide/iodate) and isotopic ratio (129I/127I) measurements using ion chromatography (IC) joined with collision/reaction cell inductively coupled plasma mass spectrometry (ICP-MS), collectively referred to as IC-ICP-MS. This approach employs online dynamically regenerated eluent suppression post chromatographic separation of the samples and collision cell technology, with pure oxygen as a collision gas for the active suppression of 129Xe (which naturally exists in the argon supplied to the ICP source) to rapidly (< 15 min) achieve precise and reproducible results. Speciated standard reference materials yielded detection limits for 127I of approximately 23.8 ng/L for iodate and 24.3 ng/L for iodide, and for 129I of approximately 1.81 ng/L for iodate and 2.62 ng/L for iodide. The method was demonstrated by analyzing groundwater samples from six wells from 129I-contaminated regions of the Hanford Site; iodate was the primary species for both 127I and 129I. Small quantities of 127I-iodide were also detected in most of the samples, but all 129I-iodide results were below the detection limit. An interference from molybdenum prevented the estimation of organo-iodine concentrations but did not affect the iodate and iodide results. This new analytical capability will enable rapid, simultaneous characterization of speciated inorganic iodine in vadose zone sediments and groundwater samples at levels below the US federal drinking water standard for 129I of 1 pCi/L (~ 5.6 ng/L).
AB - Subterranean radioiodine contamination at the Hanford Site in Washington State is believed to be present as iodide, iodate, and organo-I species, with iodate being the predominant form. Because these species have different sediment-sorption characteristics, understanding their distribution is important for developing an accurate understanding of iodine migration in the subsurface. Herein, we report a novel, rapid technique for simultaneous iodine speciation (iodide/iodate) and isotopic ratio (129I/127I) measurements using ion chromatography (IC) joined with collision/reaction cell inductively coupled plasma mass spectrometry (ICP-MS), collectively referred to as IC-ICP-MS. This approach employs online dynamically regenerated eluent suppression post chromatographic separation of the samples and collision cell technology, with pure oxygen as a collision gas for the active suppression of 129Xe (which naturally exists in the argon supplied to the ICP source) to rapidly (< 15 min) achieve precise and reproducible results. Speciated standard reference materials yielded detection limits for 127I of approximately 23.8 ng/L for iodate and 24.3 ng/L for iodide, and for 129I of approximately 1.81 ng/L for iodate and 2.62 ng/L for iodide. The method was demonstrated by analyzing groundwater samples from six wells from 129I-contaminated regions of the Hanford Site; iodate was the primary species for both 127I and 129I. Small quantities of 127I-iodide were also detected in most of the samples, but all 129I-iodide results were below the detection limit. An interference from molybdenum prevented the estimation of organo-iodine concentrations but did not affect the iodate and iodide results. This new analytical capability will enable rapid, simultaneous characterization of speciated inorganic iodine in vadose zone sediments and groundwater samples at levels below the US federal drinking water standard for 129I of 1 pCi/L (~ 5.6 ng/L).
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U2 - 10.1007/s10967-020-07537-3
DO - 10.1007/s10967-020-07537-3
M3 - Article
AN - SCOPUS:85099107952
SN - 0022-4081
VL - 327
SP - 929
EP - 937
JO - Journal of Radioanalytical Chemistry
JF - Journal of Radioanalytical Chemistry
IS - 2
ER -
