Microextraction–TQ–ICP–MS for the Direct Analysis of U and Pu from Cotton Swipes

Journal Article · Fri Oct 06 00:00:00 EDT 2023 · Analytical Chemistry

DOI:https://doi.org/10.1021/acs.analchem.3c01022· OSTI ID:2205442

Bradley, Veronica C. ^[1]; Ticknor, Brian W. ^[1]; Dunlap, Daniel R. ^[1]; Zirakparvar, N. Alex ^[1]; Metzger, Shalina C. ^[1]; Hexel, Cole R. ^[1]; Manard, Benjamin T. ^[1]

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1. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

Here, the microextraction sampling technique was integrated with triple quadrupole–inductively coupled plasma–mass spectrometry (TQ–ICP–MS) to directly sample and measure the isotopic compositions of uranium (U) and plutonium (Pu) from cotton swipes. Once extracted, the U/Pu were directed into the TQ–ICP–MS instrument for isotopic determination. Carbon dioxide (CO₂) and helium (He) gases were delivered to a collision reaction cell within the ICP–MS system for ion separation. The CO₂ reacts with the U⁺ forming UO⁺ which is ultimately separated from the Pu⁺ ions of interest in the third quadrupole. This study demonstrates direct liquid extraction of U/Pu from a solid surface and subsequent measurement by TQ–ICP–MS in <60 s. Flow rates were optimized (0.3 mL min^–1 CO₂ and 5 mL min^–1 He) in the reaction cell of the ICP–MS system to maximize the Pu signal while minimizing U interferences (i.e., ²³⁸U⁺ tail and ²³⁸UH⁺) at m/z 239. Low levels of Pu (~2 pg) were deposited on a cotton swipe along with U at concentrations ranging from 20 to 200 ng. The ²⁴⁰Pu/²³⁹Pu ratio was measured with <7% relative difference from the certified value at all U concentrations. Major and minor U isotope ratios were also measured with <4% relative difference. This highlights that the microextraction–TQ–ICP–MS method can extract a mixed U/Pu sample directly from a cotton swipe and measure both isotopic systems without chemical separation.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Office of Defense Nuclear Nonproliferation
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 2205442
• Journal Information: Analytical Chemistry, Journal Name: Analytical Chemistry Journal Issue: 43 Vol. 95; ISSN 0003-2700
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
extraction
ions
isotopes
organic polymers
plants