Sulfides: chemical ionization induced fragmentation studied with Proton Transfer Reaction-Mass Spectrometry and density functional calculations

Authors

  • Erna Schuhfried,

    1. Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Innsbruck, Austria
    Search for more papers by this author
  • Michael Probst,

    1. Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Innsbruck, Austria
    Search for more papers by this author
  • Jumras Limtrakul,

    1. Department of Chemistry and NANOTEC Center for Nanoscale Materials Design for Green Nanotechnology, Kasetsart University Bangkok, Thailand
    Search for more papers by this author
  • Sippakorn Wannakao,

    1. Department of Chemistry and NANOTEC Center for Nanoscale Materials Design for Green Nanotechnology, Kasetsart University Bangkok, Thailand
    Search for more papers by this author
  • Eugenio Aprea,

    1. IASMA Research Innovation Centre, Fondazione Edmund Mach, Food Quality and Nutrition Department, S Michele a/A, TN, Italy
    Search for more papers by this author
  • Luca Cappellin,

    1. Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Innsbruck, Austria
    2. IASMA Research Innovation Centre, Fondazione Edmund Mach, Food Quality and Nutrition Department, S Michele a/A, TN, Italy
    Search for more papers by this author
  • Tilmann D. Märk,

    1. Institut für Ionenphysik und Angewandte Physik, Leopold Franzens Universität Innsbruck, Innsbruck, Austria
    Search for more papers by this author
  • Flavia Gasperi,

    1. IASMA Research Innovation Centre, Fondazione Edmund Mach, Food Quality and Nutrition Department, S Michele a/A, TN, Italy
    Search for more papers by this author
  • Franco Biasioli

    Corresponding author
    • IASMA Research Innovation Centre, Fondazione Edmund Mach, Food Quality and Nutrition Department, S Michele a/A, TN, Italy
    Search for more papers by this author

Correspondence to: Franco Biasioli, IASMA Research Innovation Centre, Fondazione Edmund Mach, Food Quality and Nutrition Department, Via E. Mach 1, 38010, S Michele a/A, (TN), Italy. E-mail: franco.biasioli@fmach.it

Abstract

We report the energy-dependent fragmentation patterns upon protonation of eight sulfides (organosulfur compounds) in Proton Transfer Reaction-Mass Spectrometry (PTR-MS). Studies were carried out, both, experimentally with PTR-MS, and with theoretical quantum-chemical methods. Charge retention usually occurred at the sulfur-containing fragment for short chain sulfides. An exception to this is found in the unsaturated monosulfide allylmethyl sulfide (AMS), which preferentially fragmented to a carbo-cation at m/z 41, C3H5+. Quantum chemical calculations (DFT with the M062X functional 6-31G(d,p) basis sets) for the fragmentation reaction pathways of AMS indicated that the most stable protonated AMS cation at m/z 89 is a protonated (cyclic) thiirane, and that the fragmentation reaction pathways of AMS in the drift tube are kinetically controlled. The protonated parent ion MH+ is the predominant product in PTR-MS, except for diethyl disulfide at high collisional energies. The saturated monosulfides R-S-R’ (with R<R’) have little or no fragmentation, at the same time the most abundant fragment ion is the smaller R-S+ fragment. The saturated disulfides R-S-S-R display more fragmentation than the saturated monosulfides, the most common fragments are disulfide containing fragments or long-chain carbo-cations. The results rationalize fragmentation data for saturated monosulfides and disulfides and represent a detailed analysis of the fragmentation of an unsaturated sulfide. Apart from the theoretical interest, the results are in support of the quantitative analysis of sulfides with PTR-MS, all the more so as PTR-MS is one of a few techniques that allow for ultra-low quantitative analysis of sulfides. Copyright © 2013 John Wiley & Sons, Ltd.

Ancillary