Different reactivities of H3O+(H2O)(n) with unsaturated and saturated aldehydes: ligand-switching reactions govern the quantitative analytical sensitivity of SESI-MS

0570627 - ÚFCH JH 2024 RIV GB eng J - Článek v odborném periodiku
Španěl, Patrik - Dryahina, Kseniya - Omezzine Gnioua, Maroua - Smith, David
Different reactivities of H3O+(H2O)(n) with unsaturated and saturated aldehydes: ligand-switching reactions govern the quantitative analytical sensitivity of SESI-MS.
Rapid Communications in Mass Spectrometry. Roč. 37, č. 9 (2023), č. článku e9496. ISSN 0951-4198. E-ISSN 1097-0231
Grant CEP: GA ČR(CZ) GA21-25486S
Institucionální podpora: RVO:61388955
Klíčová slova: secondary electrospray ionisation mass spectrometry * selected ion flow tube mass spectrometry * ligand-switching reactions
Obor OECD: Physical chemistry
Impakt faktor: 2, rok: 2022
Způsob publikování: Open access

Rationale: The detection sensitivity of secondary electrospray ionisation mass spectrometry (SESI-MS) is much lower for saturated aldehydes than for unsaturated aldehydes. This needs to be understood in terms of gas phase ion-molecule reaction kinetics and energetics to make SESI-MS analytically more quantitative. Methods: Parallel SESI-MS and selected ion flow tube mass spectrometry (SIFT-MS) analyses were carried out of air containing variable accurately determined concentrations of saturated (C5, pentana, C7, heptanal, C8 octanal) and unsaturated (C5, 2-pentenal, C7, 2-heptenal, C8, 2-octenal) aldehyde vapours. The influence of the source gas humidity and the ion transfer capillary temperature, 250 and 300 degrees C, in a commercial SESI-MS instrument was explored. Separate experiments were carried out using SIFT to determine the rate coefficients, k(73), for the ligand-switching reactions of the H3O+(H2O)(3) ions with the six aldehydes. Results: The relative slopes of the plots of SESI-MS ion signal against SIFT-MS concentration were interpreted as the relative SESI-MS sensitivities for these six compounds. The sensitivities for the unsaturated aldehydes were 20 to 60 times greater than for the corresponding C5, C7 and C8 saturated aldehydes. Additionally, the SIFT experiments revealed that the measured k(73) are three or four times greater for the unsaturated than for the saturated aldehydes. Conclusions: The trends in SESI-MS sensitivities are rationally explained by differences in the rates of the ligand-switching reactions, which are justified by theoretically calculated equilibrium rate constants derived from thermochemical density functional theory (DFT) calculations of Gibb's free energy changes. The humidity of SESI gas thus favours the reverse reactions of the saturated aldehyde analyte ions, effectively suppressing their signals in contrast to their unsaturated counterparts.
Trvalý link: https://hdl.handle.net/11104/0341933