Electrochemically-Induced Reactions of Hexafluorophosphate Anions with Water in Negative Ion Electrospray Mass Spectrometry of Undiluted Ionic Liquids

Lu, Yuchen; King, Fred L

doi:10.1016/j.jasms.2006.02.017

Title: Electrochemically-Induced Reactions of Hexafluorophosphate Anions with Water in Negative Ion Electrospray Mass Spectrometry of Undiluted Ionic Liquids

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Abstract

The influence of water on the observed gas-phase population of negative ions in electrospray mass spectrometry was studied for the undiluted ionic liquid 1,3-butyl-methyl-imidazolium hexafluorophosphate (BMIMPF6 ). During the electrospray process, electrolytic reduction of water enhances the production of tetrafluorophosphate (F4PO), which undergoes further reactions to produce difluorophosphate (F2PO2 ) anions. These anions are observed in addition to the pre-existing hexafluorophosphate anion. The apparent substitution of two fluorine atoms with one oxygen is attributed to a series of reactions initiated by hydrolysis of hexafluorophosphate. This hydrolysis reaction was enhanced by the addition of hydroxide, formed via the hydrolysis of water or through the addition of ammonium hydroxide. The formation of FxPOy was studied as a function of the electrospray current and solution flow rate. The mass spectral response shows a quantitative logarithmic relationship between FxPOy signal intensities (adjusted for mole equivalents of H2O required) and the amount of water present, against which the water content could be rapidly assessed. Results were found to be comparable to Karl Fischer titration data

Authors:

Lu, Yuchen ^[1]; King, Fred L ^[2]

ORNL
West Virginia University

Publication Date:: Sun Jan 01 00:00:00 EST 2006

Research Org.:: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:: USDOE Office of Science (SC)

OSTI Identifier:: 959425

DOE Contract Number:: DE-AC05-00OR22725

Resource Type:: Journal Article

Journal Name:: Journal of the American Society for Mass Spectrometry

Additional Journal Information:: Journal Volume: 17; Journal Issue: 7; Journal ID: ISSN 1044-0305

Country of Publication:: United States

Language:: English

Subject:: 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; AMMONIUM HYDROXIDES; ANIONS; ATOMS; FLOW RATE; FLUORINE; HYDROLYSIS; MASS SPECTROSCOPY; OXYGEN; PRODUCTION; SPECTRAL RESPONSE; TITRATION; WATER

Citation Formats


                    Lu, Yuchen, Duckworth, Douglas, and King, Fred L. Electrochemically-Induced Reactions of Hexafluorophosphate Anions with Water in Negative Ion Electrospray Mass Spectrometry of Undiluted Ionic Liquids.  United States: N. p., 2006. 
        Web.  doi:10.1016/j.jasms.2006.02.017.

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                    Lu, Yuchen, Duckworth, Douglas, & King, Fred L. Electrochemically-Induced Reactions of Hexafluorophosphate Anions with Water in Negative Ion Electrospray Mass Spectrometry of Undiluted Ionic Liquids.  United States.  https://doi.org/10.1016/j.jasms.2006.02.017

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                    Lu, Yuchen, Duckworth, Douglas, and King, Fred L. 2006.  
        "Electrochemically-Induced Reactions of Hexafluorophosphate Anions with Water in Negative Ion Electrospray Mass Spectrometry of Undiluted Ionic Liquids".  United States.  https://doi.org/10.1016/j.jasms.2006.02.017.

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@article{osti_959425,

  title        = {Electrochemically-Induced Reactions of Hexafluorophosphate Anions with Water in Negative Ion Electrospray Mass Spectrometry of Undiluted Ionic Liquids},

  author       = {Lu, Yuchen and Duckworth, Douglas and King, Fred L},

  abstractNote = {The influence of water on the observed gas-phase population of negative ions in electrospray mass spectrometry was studied for the undiluted ionic liquid 1,3-butyl-methyl-imidazolium hexafluorophosphate (BMIMPF6 ). During the electrospray process, electrolytic reduction of water enhances the production of tetrafluorophosphate (F4PO), which undergoes further reactions to produce difluorophosphate (F2PO2 ) anions. These anions are observed in addition to the pre-existing hexafluorophosphate anion. The apparent substitution of two fluorine atoms with one oxygen is attributed to a series of reactions initiated by hydrolysis of hexafluorophosphate. This hydrolysis reaction was enhanced by the addition of hydroxide, formed via the hydrolysis of water or through the addition of ammonium hydroxide. The formation of FxPOy was studied as a function of the electrospray current and solution flow rate. The mass spectral response shows a quantitative logarithmic relationship between FxPOy signal intensities (adjusted for mole equivalents of H2O required) and the amount of water present, against which the water content could be rapidly assessed. Results were found to be comparable to Karl Fischer titration data},

  doi          = {10.1016/j.jasms.2006.02.017},

  url          = {https://www.osti.gov/biblio/959425},
  journal      = {Journal of the American Society for Mass Spectrometry},

  issn         = {1044-0305},

  number       = 7,

  volume       = 17,

  place        = {United States},

  year         = {Sun Jan 01 00:00:00 EST 2006},

  month        = {Sun Jan 01 00:00:00 EST 2006}

}

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