Chemical Characterization of Gas-phase and Condensed Organics on a Molecular Composition Level by a Next Generation PTR-MS Instrument
MARKUS MUELLER, Tobias Reinecke, Zsolt Dányi, Markus Leiminger, Klaus Winkler, Todd Rogers, Alfons Jordan,
IONICON Analytik GmbH., Innsbruck, Austria Abstract Number: 251
Working Group: Instrumentation and Methods
AbstractWe present a novel instrument for detecting gas-phase and condensed organics on a molecular composition level based on proton-transfer-reaction mass spectrometry (PTR-MS). FUSION PTR-TOF 10k (IONICON, Austria) features several enhancements compared to state-of-the-art PTR-MS technology.
The novel ion source improves the decoupling from the reaction chamber providing lowest interferences with neutrals and parasitic reagent ions. Within a single second, this source switches from quantitative proton-transfer-reaction with H
3O
+ primary reagent ions to almost fragmentation-free adduct ionization with NH
4+. Ion-molecule reactions with organics occur in a fully-controlled environment of a novel ion-focusing RF reaction chamber (FUSION) operated at reduced pressures of 2-4 mbar. This guarantees the needed clean ion chemistry with ion-molecule reactions at predictable reaction energies (E/N) and reaction rates that are crucial for quantitative operation of a PTR-MS. With these enhancements, FUSION PTR-TOF 10k achieves lowest limits of detection (< 1 pptV in 1 s) and market-leading sensitivities up to 100.000 cps/ppbV at a TOF-MS mass resolution > 10.000 m/dm.
To measure condensed organics of low volatility, FUSION PTR-TOF is equipped with the new FUSION edition of the CHemical Analysis of aeRosol ON-line (CHARON) particle inlet. CHARON allows for a direct and quantitative detection of organic sub-μm particulate matter as well as particulate nitrate at ng/m
3 levels. Non-refractive sub-μm particles in a size range > 25 nm are efficiently evaporated at controllable desorption temperatures up to 250°C.
Herein we present a thorough characterization of this CHARON FUSION PTR-TOF 10k instrument and show first application results. We highlight the ability of FUSION to sequentially analyze gas and particle phases of a limonene oxidation experiment and demonstrate the advantages of the high sensitivity combined with a pristine ion chemistry in detecting the full range of fresh SOA.