Dresden 2011 – scientific programme
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MS: Fachverband Massenspektrometrie
MS 3: Poster
MS 3.11: Poster
Monday, March 14, 2011, 16:00–18:00, P1
H3O+, NO+ and O2+ as precursor ions in PTR-MS: isomeric VOC compounds and reactions with different chemical groups — Alfons Jordan1, •Simone Jürschik1,2, Bishu Agarwal2, Gernot Hanel1, Eugen Hartungen1, Stefan Jaksch1, Lukas Märk1, Hans Seehauser1, Philipp Sulzer1, and Tilmann D. Märk1,2 — 1IONICON Analytik GmbH, Eduard-Bodem-Gasse 3, 6020 Innsbruck, Austria — 2Institut für Ionenphysik und Angewandte Physik, Leopold-Franzens Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria
Most PTR-MS instruments employed so far use an ion source consisting of a hollow cathode discharge in water vapour which provides an intense source of protonated water (H3O+). However, the use of other ions, e.g. NO+ and O2+, can be useful for the identification of VOCs, for separation of isomers and for the detection of VOCs with proton affinities below that of H2O.
In general the main advantage of O2+ is to see compounds which are not measureable with protonated water. For example nearly all halogenated hydrocarbons are detectable with O2+ whereas just the very large ones and the aromatic halogenated compounds are detectable with H3O+. By using NO+ as precursor ion in nearly all cases the product ions are different from the product ion by using protonated water. Very often also isomeric compounds show different product ions. For instance, isomers like aldehydes and ketones or acids and esters show in many cases different product ions in the reaction with NO+.