Interrogating Proton Affinities of Organophosphonate Species Via Atmospheric Flow Tube Mass Spectrometry and Computational Methods

  • Kelsey A. Morrison
  • Benjamin J. Bythell
  • Brian H. ClowersEmail author
Research Article


Within trace vapor analysis in environmental monitoring, defense, and industry, atmospheric flow tube mass spectrometry (AFT-MS) can fill a role that incorporates non-contact vapor analysis with the selectivity and low detection limits of mass spectrometry. AFT-MS has been applied to quantitating certain explosives by selective clustering with nitrate and more recently applied to detecting tributyl phosphate and dimethyl methylphosphonate as protonated species. Developing AFT-MS methods for organophosphorus species is appealing, given that this class of compounds includes a range of pollutants, chemical warfare agent (CWA) simulants, and CWA degradation products. A key aspect of targeting organophosphorus analytes has included the use of dopant ion chemistry to form adducts that impart additional analytical selectivity. The assessment of potential dopant molecules suited to enhance detection of these compounds is hindered by few published ion thermochemical properties for organophosphorus species, such as proton affinity, which can be used for approximating proton-bound dimer bond strength. As a preliminary investigation for the progression of sensing methods involving AFT-MS, we have applied both the extended kinetic method and computational approaches to eight organophosphorus CWA simulants to determine their respective gas-phase proton affinities. Notable observed trends, supported by computational efforts, include an increase in proton affinity as the alkyl chain lengths on the phosphonates increased.

Graphical Abstract



Ambient vapor sampling Dielectric barrier discharge ionization (DBDI) Mass spectrometry Proton affinity (PA) Extended kinetic method Phosphonates Gas-phase clustering Computational chemistry 



Funding for K. A. M. was provided in part by the Army Research Office (Award No. W911NF1510619).

Supplementary material

13361_2019_2202_MOESM1_ESM.docx (47 kb)
ESM 1 (DOCX 46 kb)
13361_2019_2202_MOESM2_ESM.xlsx (42 kb)
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  1. 1.
    Braley, J.C., Grimes, T.S., Nash, K.L.: Alternatives to HDEHP and DTPA for simplified TALSPEAK separations. Ind. Eng. Chem. Res. 51, 629–638 (2012)CrossRefGoogle Scholar
  2. 2.
    Vucinic, S., Antonijevic, B., Tsatsakis, A.M., Vassilopoulou, L., Docea, A.O., Nosyrev, A.E., Izotov, B.N., Thiermann, H., Drakoulis, N., Brkic, D.: Environmental exposure to organophosphorus nerve agents. Environ. Toxicol. Pharmacol. 56, 163–171 (2017)CrossRefGoogle Scholar
  3. 3.
    Crawford Jr., C.L., Hill, H.H.: Homeland security. In: Lee, M.S. (ed.) Mass spectrometry handbook, pp. 441–475. John Wiley & Sons, Inc (2012)Google Scholar
  4. 4.
    Marklund, A., Andersson, B., Haglund, P.: Screening of organophosphorus compounds and their distribution in various indoor environments. Chemosphere. 53, 1137–1146 (2003)CrossRefGoogle Scholar
  5. 5.
    Munro, N.B., Talmage, S.S., Griffin, G.D., Waters, L.C., Watson, A.P., King, J.F., Hauschild, V.: The sources, fate, and toxicity of chemical warfare agent degradation products. Environ. Health Perspect. 107, 933–974 (1999)CrossRefGoogle Scholar
  6. 6.
    Hakonen, A., Andersson, P.O., Stenbæk Schmidt, M., Rindzevicius, T., Käll, M.: Explosive and chemical threat detection by surface-enhanced Raman scattering: a review. Anal. Chim. Acta. 893, 1–13 (2015)CrossRefGoogle Scholar
  7. 7.
    Holthoff, E., Bender, J., Pellegrino, P., Fisher, A.: Quantum cascade laser-based photoacoustic spectroscopy for trace vapor detection and molecular discrimination. 1986–2002 (2010).
  8. 8.
    Steiner, W.E., Clowers, B.H., Haigh, P.E., Hill, H.H.: Secondary ionization of chemical warfare agent simulants: atmospheric pressure ion mobility time-of-flight mass spectrometry. Anal. Chem. 75, 6068–6076 (2003)CrossRefGoogle Scholar
  9. 9.
    Wolf, J.C., Schaer, M., Siegenthaler, P., Zenobi, R.: Direct quantification of chemical warfare agents and related compounds at low ppt levels: comparing active capillary dielectric barrier discharge plasma ionization and secondary electrospray ionization mass spectrometry. Anal. Chem. 87, 723–729 (2015)CrossRefGoogle Scholar
  10. 10.
    Cordell, R.L., Willis, K.A., Wyche, K.P., Blake, R.S., Ellis, A.M., Monks, P.S.: Detection of chemical weapon agents and simulants using chemical ionization reaction time-of-flight mass spectrometry. Anal. Chem. 79, 8359–8366 (2007)CrossRefGoogle Scholar
  11. 11.
    Ringer, J.M.: Detection of nerve agents using proton transfer reaction mass spectrometry with ammonia as reagent gas. Eur. J. Mass Spectrom. 19, 175–185 (2013)CrossRefGoogle Scholar
  12. 12.
    Kassebacher, T., Sulzer, P., Jürschik, S., Hartungen, E., Jordan, A., Edtbauer, A., Feil, S., Hanel, G., Jaksch, S., Märk, L., Mayhew, C.A., Märk, T.D.: Investigations of chemical warfare agents and toxic industrial compounds with proton-transfer-reaction mass spectrometry for a real-time threat monitoring scenario. Rapid Commun. Mass Spectrom. 27, 325–332 (2013)CrossRefGoogle Scholar
  13. 13.
    Ewing, R.G., Clowers, B.H., Atkinson, D.A.: Direct real-time detection of vapors from explosive compounds. Anal. Chem. 85, 10977–10983 (2013)CrossRefGoogle Scholar
  14. 14.
    Ewing, R.G., Atkinson, D.A., Clowers, B.H.: Direct real-time detection of RDX vapors under ambient conditions. Anal. Chem. 85, 389–397 (2013)CrossRefGoogle Scholar
  15. 15.
    Ewing, R.G., Valenzuela, B.R., Atkinson, D.A., Freeburg, E.D.W.: Detection of inorganic salt based home made explosives (HME) by atmospheric flow tube–mass spectrometry detection of inorganic salt based home made explosives (HME) by atmospheric flow tube–mass spectrometry. Anal. Chem. (2018).
  16. 16.
    Ewing, R.G., Valenzuela, B.R.: Selective reagent ions for the direct vapor detection of organophosphorus compounds below parts-per-trillion levels. Anal. Chem. 90, 7583–7590 (2018)CrossRefGoogle Scholar
  17. 17.
    Morrison, K.A., Clowers, B.H.: Characterization of alkylphosphonic acid vapors using atmospheric flow tube-ion trap mass spectrometry. Rapid Commun. Mass Spectrom. (2018).
  18. 18.
    Ewing, R.G., Heredia-Langner, A., Warner, M.G.: Optimizing detection of RDX vapors using designed experiments for remote sensing. Analyst. 139, 2440–2448 (2014)CrossRefGoogle Scholar
  19. 19.
    Meot-Ner, M.: The proton affinity scale, and effects of ion structure and solvation. Int. J. Mass Spectrom. 227, 525–554 (2003)CrossRefGoogle Scholar
  20. 20.
    Hodges, R.V., McDonnell, T.J., Beauchamp, J.L.: Properties and reactions of trimethyl phosphite, trimethyl phosphate, triethyl phosphate, and trimethyl phosphorothionate by ion cyclotron resonance spectroscopy. J. Am. Chem. Soc. 102, 1327–1332 (1980)CrossRefGoogle Scholar
  21. 21.
    Tabrizchi, M., Shooshtari, S.: Proton affinity measurements using ion mobility spectrometry. J. Chem. Thermodyn. 35, 863–870 (2003)CrossRefGoogle Scholar
  22. 22.
    Hunter, E.P., Lias, S.G.: Evaluated gas phase basicities and proton affinities of molecules: an update. J. Phys. Chem. Ref. Data. 27, 413–656 (1998)CrossRefGoogle Scholar
  23. 23.
    Lesage, D., Virelizier, H., Tabet, J.C., Jankowski, C.K., Wiley, J.: Study of mass spectrometric fragmentations of tributyl phosphate via collision-induced dissociation. Rapid Commun. Mass Spectrom. 15, 1947–1956 (2001)CrossRefGoogle Scholar
  24. 24.
    Cheng, X., Wu, Z., Fenselau, C.: Collision energy dependence of proton-bound dimer dissociation: entropy effects, proton affinities, and intramolecular hydrogen-bonding in protonated peptides. J. Am. Chem. Soc. 115, 4844–4848 (1993)CrossRefGoogle Scholar
  25. 25.
    Armentrout, P.B.: Entropy measurements and the kinetic method: a statistically meaningful approach. J. Am. Soc. Mass Spectrom. 11, 371–379 (2000)CrossRefGoogle Scholar
  26. 26.
    Ervin, K.M., Armentrout, P.B.: Systematic and random errors in ion affinities and activation entropies from the extended kinetic method. J. Mass Spectrom. 39, 1004–1015 (2004)CrossRefGoogle Scholar
  27. 27.
    Bourgoin-Voillard, S., Afonso, C., Lesage, D., Zins, E.L., Tabet, J.C., Armentrout, P.B.: Critical evaluation of kinetic method measurements: possible origins of nonlinear effects. J. Am. Soc. Mass Spectrom. 24, 365–380 (2013)CrossRefGoogle Scholar
  28. 28.
    Kertesz, T.M., Hall, L.H., Hill, D.W., Grant, D.F.: CE50: quantifying collision induced dissociation energy for small molecule characterization and identification. J. Am. Soc. Mass Spectrom. 20, 1759–1767 (2009)CrossRefGoogle Scholar
  29. 29.
    Zhu, Y., Yang, Z., Rodgers, M.T.: Influence of linkage stereochemistry and protecting groups on glycosidic bond stability of sodium cationized glycosyl phosphates. J. Am. Soc. Mass Spectrom. 2602–2613 (2017).
  30. 30.
    McLuckey, S.A., Cameron, D., Cooks, R.G.: Proton affinities from dissociations of proton-bound dimers. J. Am. Chem. Soc. 103, 1313–1317 (1981)CrossRefGoogle Scholar
  31. 31.
    Zhao, Y., Truhlar, D.G.: The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and transition elements: two new functionals and systematic testing of four M06-class functionals and 12 other function. Theor. Chem. Accounts. 120, 215–241 (2008)CrossRefGoogle Scholar
  32. 32.
    Skene, W.G., Krzymien, M.E.: Vapor pressure of tri-n-butyl phosphate. J. Chem. Eng. Data. 40, 394–397 (1995)CrossRefGoogle Scholar
  33. 33.
    Nichols, C.M., Old, W.M., Lineberger, W.C., Bierbaum, V.M.: Gas-phase acidities of nitrated azoles as determined by the extended kinetic method and computations. J. Phys. Chem. A. 119, 395–402 (2015)CrossRefGoogle Scholar
  34. 34.
    Rabus, J.M., Abutokaikah, M.T., Ross, R.T., Bythell, B.J.: Sodium-cationized carbohydrate gas-phase fragmentation chemistry: influence of glycosidic linkage position. Phys. Chem. Chem. Phys. 19, 25643–25652 (2017)CrossRefGoogle Scholar
  35. 35.
    Bythell, B.J., Rabus, J.M., Wagoner, A.R., Abutokaikah, M.T., Maître, P.: Sequence ion structures and dissociation chemistry of deprotonated sucrose anions. J. Am. Soc. Mass Spectrom. 29, 2380–2393 (2018)CrossRefGoogle Scholar
  36. 36.
    Rabus, J.M., Simmons, D.R., Maître, P., Bythell, B.J.: Deprotonated carbohydrate anion fragmentation chemistry: structural evidence from tandem mass spectrometry, infra-red spectroscopy, and theory. Phys. Chem. Chem. Phys. 20, 27897–27909 (2018)CrossRefGoogle Scholar
  37. 37.
    Supady, A.: adrianasupady/fafoom,
  38. 38.
    Marianski, M., Supady, A., Ingram, T., Schneider, M., Baldauf, C.: Assessing the accuracy of across-the-scale methods for predicting carbohydrate conformational energies for the examples of glucose and α-maltose. J. Chem. Theory Comput. 12, 6157–6168 (2016)CrossRefGoogle Scholar
  39. 39.
    Supady, A., Blum, V., Baldauf, C.: First-principles molecular structure search with a genetic algorithm. J. Chem. Inf. Model. 55, 2338–2348 (2015)CrossRefGoogle Scholar
  40. 40.
    Halgren, T.A.: Merck molecular force field. I. Basis, form, scope, parameterization, and performance of MMFF94. J. Comput. Chem. 17, 490–519 (1996)CrossRefGoogle Scholar
  41. 41.
    Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A., Cheeseman, J.R., Scalmani, G., Barone, V., Mennucci, B., Petersson, G.A., Nakatsuji, H., Caricato, M., Li, X., Hratchian, H.P., Izmaylov, A.F., Bloino, J., Zheng, G., Sonnenberg, J.L., Hada, M., Ehara, M., Toyota, K., Fukuda, R., Hasegawa, J., Ishida, M., Nakajima, T., Honda, Y., Kitao, O., Nakai, H., Vreven, T., Montgomery, J.A., Peralta, J.E., Ogliaro, F., Bearpark, M., Heyd, J.J., Brothers, E., Kudin, K.N., Staroverov, V.N., Kobayashi, R., Normand, J., Raghavachari, K., Rendell, A., Burant, J.C., Iyengar, S.S., Tomasi, J., Cossi, M., Rega, N., Millam, J.M., Klene, M., Knox, J.E., Cross, J.B., Bakken, V., Adamo, C., Jaramillo, J., Gomperts, R., Stratmann, R.E., Yazyev, O., Austin, A.J., Cammi, R., Pomelli, C., Ochterski, J.W., Martin, R.L., Morokuma, K., Zakrzewski, V.G., Voth, G.A., Salvador, P., Dannenberg, J.J., Dapprich, S., Daniels, A.D., Farkas, Foresman, J.B., Ortiz, J. V., Cioslowski, J., Fox, D.J.: Gaussian 09, (2009)Google Scholar
  42. 42.
    Lias, S.G., Bartmess, J.E., Liebman, J.F., Holmes, J.L., Levin, R.D., Mallard, W.G.: Gas-phase ion and neutral thermochemistry (1988)Google Scholar
  43. 43.
    Ervin, K.M.: Microcanonical analysis of the kinetic method. The meaning of the “apparent entropy”. J. Am. Soc. Mass Spectrom. 13, 435–452 (2002)CrossRefGoogle Scholar
  44. 44.
    Toomsalu, E., Koppel, I.A., Burk, P.: Critical test of some computational chemistry methods for prediction of gas-phase acidities and basicities. J. Chem. Theory Comput. 9, 3947–3958 (2013)CrossRefGoogle Scholar
  45. 45.
    Gronert, S.: An ab initio study of proton transfers from gas-phase dications: complications in kinetic methods for determining acidities. J. Am. Chem. Soc. 118, 3525–3526 (1996)CrossRefGoogle Scholar
  46. 46.
    Midey, A.J., Miller, T.M., Viggiano, A.A.: Kinetics of ion-molecule reactions with dimethyl methylphosphonate at 298 K for chemical ionization mass spectrometry detection of GX. J. Phys. Chem. A. 113, 4982–4989 (2009)CrossRefGoogle Scholar
  47. 47.
    Midey, A.J., Miller, T.M., Viggiano, A.A.: Survey of ion energetics properties of chemical weapon agent (CWA) breakdown products using G3(MP2) theory. Int. J. Mass Spectrom. 315, 1–7 (2012)CrossRefGoogle Scholar
  48. 48.
    Morrison, K.A., Ewing, R.G., Clowers, B.H.: Ambient vapor sampling and selective cluster formation for the trace detection of tributyl phosphate via atmospheric flow tube mass spectrometry. Talanta. 195, 683–690 (2019)CrossRefGoogle Scholar

Copyright information

© American Society for Mass Spectrometry 2019

Authors and Affiliations

  • Kelsey A. Morrison
    • 1
  • Benjamin J. Bythell
    • 2
  • Brian H. Clowers
    • 1
    Email author
  1. 1.Washington State UniversityPullmanUSA
  2. 2.University of MissouriSt. LouisUSA

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