Technical Note: Detection and identification of radical species formed from α-pinene/ozone reaction using DMPO spin trap
Item
Title (Dublin Core)
Technical Note: Detection and identification of radical species formed from α-pinene/ozone reaction using DMPO spin trap
Description (Dublin Core)
The reactions of ozone with monoterpenes proceed via the formation of multiple oxygen- and carbon-centered free radical species. These radical species are highly reactive and thus, have generally not been measureable. A method for their detection and characterization is needed to preserve these radicals for a sufficiently long time to permit analyzes to be performed. Radical-addition reactions, also called spin trapping techniques, allow the detection of short-lived radicals. This approach has been applied to products from the α-pinene/ozone reaction. Secondary organic aerosol (SOA) from a reaction chamber was collected on quartz fiber filters and extracted with a solution of 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) (spin trap) followed by analysis with ion-trap tandem mass spectrometry (MS<sup>n</sup>) using electrospray ionization (ESI) in the positive scan mode. The DMPO adducts with radical species appear as positive ions [DMPO−R+H]<sup>+</sup>, [DMPO−OR+H]<sup>+</sup> and [DMPO−O−OR+H]<sup>+</sup> in full MS spectra of the samples. Tandem mass spectrometry (MS<sup>2</sup>) was performed to identify the radical species. The DMPO adducts with the C-centered radical species [DMPO−R+H]<sup>+</sup> are characterized by <i>m/z</i> 114 [DMPO+H]<sup>+</sup> in the MS<sup>2</sup> spectra and with peaks that represent the loss of [DMPO+H]<sup>+</sup>. The DMPO adducts with O-centered radical species (RO· and ROO·) are identified by <i>m/z</i> 130 [DMPO−OH+H]<sup>+</sup> and <i>m/z</i> 146 [DMPO−O−OH+H]<sup>+</sup>, respectively, and with peaks that correspond to the loss of those adducts. DMPO was also able to capture OH radicals from the particle phase, and the product ion fragmentation confirmed DMPO/OH structure providing evidence for particle-bound OH radicals.
Creator (Dublin Core)
Pavlovic, J.
Hopke, P. K.
Date (Dublin Core)
2018-08-10
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acpd-9-23695-2009
https://acp.copernicus.org/preprints/acp-2009-558/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
