Proton transfer reaction mass spectrometry investigations on the effects of reduced electric field and reagent ion internal energy on product ion branching ratios for a series of saturated alcohols

Fragmentation, auto-modification and post ionisation proton bound dimer ion formation: the differential mobility spectrometry of low molecular weight alcohols

“…The protonated monomer may undergo a dehydration reaction (6) resulting in a fragment ion (m/z 43), reported previously in PTRMS studies at electric fields of 138 Td [27].…”

“…The instruments used in this study were not able to isolate and characterise fully the ion clusters observed; this will require the design and construction of a new DMS-MS instrument that isolates the product ions from neutral species before the ion filter. The underlying processes that generated the observed responses may be described in similar terms to the chemistry of alcohol product ions observed with PTRMS [27]. At low and ion filter temperature the predominant propan-1-ol species appears to be a proton bound dimer (m/z 14 121), increasing the energy of the ion cluster causes dissociation generating a product (m/z 61) thought to be a protonated monomer (5) (5).…”

“…Proton bound dimers were also not reported within 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 15 The m/z 39 fragment (C3H3 + ) was observed with PTRMS studies at electric fields of 138 Td [27], and is thought to result from the sequential loss of H2 (8) and at this stage the tentative assignment for C3H3 + is a cyclic entity [34,35].…”

“…Previous studies with proton transfer reaction mass spectrometry described the dehydration of protonated alcohols above electric-field strength of 92 Td, followed by dehydrogenation when the electric-field strength was increased above 138 Td [27]. The combined effect of temperature and electric-field was not described.…”

“…As ion energy, expressed as effective ion temperature ( ), is increased alcohol product ions decompose, and findings from proton transfer reaction mass spectrometry [26,27] describe the dehydration of protonated monomers with increasing electric field ( / ) strength; was increased, see (3) and (4). As energies are increased ( ), the protonated alkene can fragment further, (4).…”