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Title: Generation of gas-phase zirconium fluoroanions by electrospray of an ionic liquid

RATIONALE: When measuring extremely wide isotope ratios (= 1 x 109) accelerator mass spectrometry (AMS) is the instrument of choice, however it requires an anion for injection into the tandem accelerator. Since many elements do not have positive electronegativities they do not form stable negative atomic ions, and hence are not compatible for isotope ratio measurement using AMS. Thus new approaches for forming anions are sought; fluoroanions are particularly attractive because fluorine is monoisotopic, and thus will not have overlapping isobars with the isotope of interest. METHODS: An approach is described for making zirconium fluoroanions using the fluorinating ionic liquid (IL) 1-ethyl-3-methylimidazolium fluorohydrogenate, which was used to generate abundant [ZrF5-] using electrospray ionization. The IL was dissolved in acetonitrile, combined with a dilute solution of either Zr4+ or ZrO2+, and then electrosprayed. Mass analysis and collision induced dissociation were conducted using a time-of-flight mass spectrometer. Cluster structures were predicted using density functional theory calculations. RESULTS: The fluorohydrogenate IL solutions generated abundant [ZrF5-] starting from solutions of both Zr4+ and ZrO2+. The mass spectra also contained IL-bearing cluster ions, whose compositions indicated the presence of [ZrF6]2- in solution, a conclusion supported by the structural calculations. Rinsing out the zirconium-IL solution withmore » acetonitrile decreased the IL clusters, but enhanced [ZrF5]-, which was sorbed by the polymeric electrospray supply capillary, and then released upon rinsing. This reduced the ion background in the mass spectrum. CONCLUSIONS: The fluorohydrogenate-IL solutions are a facile way to form zirconium fluoroanions in the gas phase using electrospray. The approach has potential as a source of fluoroanions for injection into an AMS, which would enable high-sensitivity measurement of minor zirconium isotopes, and benefits from the absence of overlapping isobars caused by the charge carrier (i.e., the monoisotopic fluorine atoms).« less
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Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0951-4198
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Rapid Communications in Mass Spectrometry; Journal Volume: 28; Journal Issue: 11
Research Org:
Idaho National Laboratory (INL)
Sponsoring Org:
Country of Publication:
United States
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; Density Functional Theory Calculations; Electrospray Ionization Mass Spectrometry; Fluoroanion; Fluorohydrogenate; Ionic Liquid; Isotope Ratio