Sensitivity of SESI-MS to a range of volatile organic compounds: ligand switching ion chemistry and the influence of Zspray™ guiding E-fields
Kseniya Dryahina, Miroslav Polášek, David Smith, Patrik Španěl
Abstract:
Secondary electrospray ionization (SESI) is currently only semi-quantitative. In the Zspray™ arrangement of SESI-MS, the transfer of ions from near atmospheric pressure to a triple quadrupole is achieved by guiding E-fields that partially desolvate both reagent and analyte ions which must be understood. Also, to make SESI-MS more quantitative, the mechanisms and the kinetics of the reaction processes, especially ligand switching reactions of the hydrated hydronium reagent ions, H3O+(H2O)n, with VOC molecules, need to be understood.
Methods:
A modified Zspray™ ESI ions source operating at sub-atmospheric pressure with analyte sample gas introduced via an inlet coaxial with the spray is used. Variation of the ion guiding E-fields was used to reveal the degree of desolvation of both reagent and analyte ions. The instrument sensitivity was determined for several classes of VOCs by introducing bag samples of suitably varying concentrations as quantified on-line using SIFT-MS.