JpGU-AGU Joint Meeting 2020

Presentation information

[E] Oral

A (Atmospheric and Hydrospheric Sciences ) » A-AS Atmospheric Sciences, Meteorology & Atmospheric Environment

[A-AS07] Atmospheric Chemistry

convener:Naoko Saitoh(Center for Environmental Remote Sensing), Tomoki Nakayama(Graduate School of Fisheries and Environmental Sciences, Nagasaki University), Sakae Toyoda(Department of Chemical Science and Engineering, Tokyo Institute of Technology), Risa Uchida(Japan Automobile Research Institute)

[AAS07-25] Accurate Identification of Dimers from α-Pinene Oxidation Using High-Resolution Collision-Induced Dissociation Mass Spectrometry

*Kanako Sekimoto1,2, Daisuke Fukuyama1, Satoshi Inomata3 (1.Yokohama City University, 2.Osaka University, 3.National Institute for Environmental Studies)

Keywords:α-Pinene, Oxidation, Dimer, High-resolution collision-induced dissociation mass spectrometry, Hydrogen-bonded artifact cluster

Highly oxidized dimers from α-pinene oxidation are essential to the atmospheric chemistry field because they are efficient precursors of secondary organic aerosols. Here we apply high-resolution collision-induced dissociation (CID) mass spectrometry with an atmospheric pressure ionization (API) source to accurately identify the origin of dimers from α-pinene + O3/OH/NOx reactions. The CID spectra and specific fragmentation patterns suggest that (i) a large fraction of dimer ions detected in full-scan mass spectra can be hydrogen-bonded clusters, which are instrument artifacts; these clusters form owing to the adiabatic expansion between the API source inside a mass spectrometer, and (ii) the residual small fraction includes covalently-bonded dimers, such as hydroperoxide-type dimers, that are formed from reactions between a stabilized Criegee Intermediate (sCI) and oxidized monomers. This work highlights the importance of accurate identification and quantification of dimers for mechanistic and kinetic studies of α-pinene-derived dimer formation using ion intensities detected by mass spectrometry.