Excitation, separation and fragmentation of ions by drift fields in SIFT-MS for immediate selective trace gas quantification

Abstract:
The aim of the project is to reveal new physical principles applicable to immediate, simultaneous and separate quantification of the individual components of mixtures of volatile compounds in air and exhaled breath by selected ion flow tube mass spectrometry, SIFT-MS. An experimental apparatus will be constructed that allows stablishment of electric drift fields (E) in the SIFT-MS flow tube. The mobility in helium of the product ions of the reactions of H3O+, O2+ and NO+ with different trace compounds and of the hydrates of these product ions will be studied as a function of E. Collisional dissociation of these ions will be also studied. Analytical methods will be developed to interpret the modifications of mass spectra resulting from timevarying E-fields within the flow tube, which will allow identification of overlapping isobaric product ions. The efficacy of this new analytical approach will be validated using mixtures of known composition and its utility explored for the analysis of VOCs present in exhaled breath and in the headspace of food products and bacterial cultures.

Goals:
To describe the dependencies of the mobilities in helium of the product ions of the reactions of H3O+, O2+• and NO+ with different VOCs and of the hydrates of such product ionson the strength of the electric field. To identify of overlapping isobaric ions.