RATIONALE: Secondary electrospray ionization (SESI) in a water spray environment at atmospheric pressure involves the reactions of hydrated hydronium reagent ions, H3 O+ (H2 O)n , with trace analyte compounds in air samples. Understanding the formation and dehydration of reagent and analyte ions is the foundation for meaningful quantification of trace compounds by SESI-mass spectrometry (MS). METHODS: A numerical model based on gas-phase ion thermochemistry is developed that describes equilibria in H3 O+ (H2 O)n reagent cluster ion distributions and ligand switching reactions with polar NH3 molecules leading to equilibrated hydrated ammonium ions NH4 + (H2 O)m . The model predictions are compared with experimental results obtained using a cylindrical SESI source coupled to an ion-trap mass spectrometer via a heated ion transfer capillary. Non-polar isoprene, C5 H8 , was used to further probe the nature of the reagent ions. RESULTS: Equilibrium distributions of H3 O+ (H2 O)n ions and their reactions with NH3 molecules have been characterized by the model in the near-atmospheric pressure SESI source. NH3 analyte molecules displace H2 O ligands from the H3 O+ (H2 O)n ions at the collisional rate forming NH4 + (H2 O)m ions, which travel through the heated ion transfer capillary losing H2 O molecules. The data for variable NH3 concentrations match the model predictions and the C5 H8 test substantiates the notion of dehydration in the heated capillary. CONCLUSIONS: Large cluster ions formed in the SESI region are dehydrated to H3 O+ (H2 O)1,2,3 and NH4 + (H2 O)1,2 while passing through the heated capillary, and considerable diffusion losses also occur. This phenomenon is also predicted for other polar analyte molecules, A, that can undergo similar switching reactions, thus forming AH+ and AH+ (H2 O)m analyte ions.

J Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences Dolejškova 3 Prague 8 18223 Czech Republic

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Fenn JB, Mann M, Meng CK, Wong SF, Whitehouse CM. Electrospray ionization for mass-spectrometry of large biomolecules. Science. 1989;246(4926):64-71.

Fenn JB, Mann M, Meng CK, Wong SF, Whitehouse CM. Electrospray ionization - Principles and practice. Mass Spectrom Rev. 1990;9(1):37-70.

Wu C, Siems WF, Hill HH. Secondary electrospray ionization ion mobility spectrometry/mass spectrometry of illicit drugs. Anal Chem. 2000;72(2):396-403.

Bruderer T, Gaisl T, Gaugg MT, et al. On-line analysis of exhaled breath. Chem Rev. 2019;119(19):10803-10828.

Rioseras AT, Singh KD, Nowak N, et al. Real-time monitoring of tricarboxylic acid metabolites in exhaled breath. Anal Chem. 2018;90(11):6453-6460.

Bregy L, Muggler AR, Martinez-Lozano Sinues P, et al. Differentiation of oral bacteria in in vitro cultures and human saliva by secondary electrospray ionization- mass spectrometry. Sci Rep. 2015;5(1):15163.

Bregy L, Nussbaumer-Ochsner Y, Martinez-Lozano Sinues P, et al. Real-time mass spectrometric identification of metabolites characteristic of chronic obstructive pulmonary disease in exhaled breath. Clin Mass Spectrom. 2018;7:29-35.

Lan J, Parte FB, Vidal-de-Miguel G, Zenobi R. Secondary electrospray ionization. In: Beauchamp J, Davis C, Pleil J, (Eds.) Breathborne Biomarkers and the Human Volatilome. 2nd ed. Boston: Elsevier; 2020:185-199.

Rioseras AT, Gaugg MT, Martinez-Lozano Sinues P. Secondary electrospray ionization proceeds via gas-phase chemical ionization. Anal Methods. 2017;9(34):5052-5057.

Kebarle P, Verkerk UH. Electrospray: From ions in solution to ions in the gas phase, what we know now. Mass Spectrom Rev. 2009;28(6):898-917.

Smith D, Adams NG, Henchman MJ. Studies of the binary reactions of H3O+(H2O)0,1,2 ions and their deuterated analogs with D2O, H2O, and NH3. J Chem Phys. 1980;72(9):4951-4957.

Smith D, McEwan MJ, Španěl P. Understanding gas phase ion chemistry is the key to reliable selected ion flow tube-mass spectrometry analyses. Anal Chem. 2020;92(19):12750-12762.

Davies SJ, Španěl P, Smith D. Breath analysis of ammonia, volatile organic compounds and deuterated water vapor in chronic kidney disease and during dialysis. Bioanalysis. 2014;6(6):843-857.

Španěl P, Dryahina K, Smith D. Acetone, ammonia and hydrogen cyanide in exhaled breath of several volunteers aged 4-83 years. J Breath Res. 2007;1(1):011001.

Dryahina K, Sovová K, Nemec A, Španěl P. Differentiation of pulmonary bacterial pathogens in cystic fibrosis by volatile metabolites emitted by their in vitro cultures: Pseudomonas aeruginosa, Staphylococcus aureus, Stenotrophomonas maltophilia and the Burkholderia cepacia complex. J Breath Res. 2016;10(3):037102.

Dryahina K, Som S, Smith D, Spanel P. Characterization of spoilage-related volatile organic compounds in packaged leaf salads. Flavour Fragr J. 2020;35(1):24-33.

Martinez-Lozano Sinues P, de la Mora JF. Electrospray ionization of volatiles in breath. Int J Mass Spectrom. 2007;265(1):68-72.

Michalcikova RB, Dryahina K, Smith D, Spanel P. Volatile compounds released by Nalophan; implications for selected ion flow tube mass spectrometry and other chemical ionisation mass spectrometry analytical methods. Rapid Commun Mass Spectrom. 2020;34(5):e8602.

Som S, Kubišta J, Dryahina K, Španěl P. Parallel secondary electrospray ionisation mass spectrometry and selected ion flow tube mass spectrometry quantification of trace amounts of volatile ketones. Rapid Commun Mass Spectrom. 2021;35:e8981.

Davies S, Španěl P, Smith D. Quantitative analysis of ammonia on the breath of patients in end-stage renal failure. Kidney Int. 1997;52(1):223-228.

Španěl P, Smith D. Quantification of volatile metabolites in exhaled breath by selected ion flow tube mass spectrometry, SIFT-MS. Clin Mass Spectrom. 2020;16:18-24.

Lee EPF, Dyke JM, Wilders AE, Watts P. Ab initio calculation of relative ion concentrations of protonated water clusters at equilibrium. Mol Phys. 1990;71(1):207-215.

Kebarle P, Searles SK, Zolla A, Scarborough J, Arshadi M. The solvation of the hydrogen ion by water molecules in the gas phase. Heats and entropies of solvation of individual reactions: H+(H2O)n-1 + H2O → H+(H2O)n. J Am Chem Soc. 1967;89(25):6393-6399.

Hiraoka K. Fundamentals of Mass Spectrometry. New York: Springer; 2013.

Mautner M. The ionic hydrogen bond and ion solvation. 2. Solvation of onium ions by one to seven water molecules. Relations between monomolecular, specific, and bulk hydrogen. J Am Chem Soc. 1984;106(5):1265-1272.

Harvey AH, Thermodynamic Properties of Water. NISTIR 5078. NIST/ASME Steam Properties: National Institute of Standards and Technology Database. 1998.

Keenan JH. Steam Tables: Thermodynamic Properties of Water, Including Vapor, Liquid, and Solid Phases. New York: Wiley; 1969.

Bouchoux G, Salpin JY, Leblanc D. A relationship between the kinetics and thermochemistry of proton transfer reactions in the gas phase. Int J Mass Spectrom Ion Process es. 1996;153(1):37-48.

Španěl P, Smith D. Reactions of hydrated hydronium ions and hydrated hydroxide ions, with some hydrocarbons and oxygen-bearing organic-molecules. J Phys Chem. 1995;99(42):15551-15556.

Su T, Chesnavich WJ. Parametrization of the ion-polar molecule collision rate-constant by trajectory calculations. J Chem Phys. 1982;76(10):5183-5185.

Johnson III RD, NIST Computational Chemistry Comparison and Benchmark Database, NIST Standard Reference Database Number 101. 2020.

Smith D, Španěl P, Hanna GB, Dweik R. Selected ion flow tube mass spectrometry. In: Beauchamp J, Davis C, Pleil J, (Eds.) Breathborne Biomarkers and the Human Volatilome. 2nd ed. Boston: Elsevier; 2020:137-153.

Bernier L, Pinfold H, Pauly M, Rauschenbach S, Reiss J. Gas flow and ion transfer in heated ESI capillary interfaces. J Am Soc Mass Spectrom. 2018;29(4):761-773.

Curtiss LA, Frurip DJ, Blander M. Studies of molecular association in H2O and D2O vapors by measurement of thermal conductivity. J Chem Phys. 1979;71(6):2703-2711.

Španěl P, Zabka J, Zymak I, Smith D. Selected ion flow tube study of the reactions of H3O+ and NO+ with a series of primary alcohols in the presence of water vapour in support of selected ion flow tube mass spectrometry. Rapid Commun Mass Spectrom. 2017;31(5):437-446.

Španěl P, Smith D. Influence of weakly bound adduct ions on breath trace gas analysis by selected ion flow tube mass spectrometry (SIFT-MS). Int J Mass Spectrom. 2009;280(1-3):128-135.