Characterization of products formed in the reaction of ozone with α-pinene: case for organic peroxides

Abstract

The generation of reactive oxygen species (ROS) and their subsequent induced pulmonary and systemic oxidative stress has been implicated as an important molecular mechanism of PM-mediated toxicity. However, recent work has shown that there is significant ROS associated with ambient PM. In order to understand the formation mechanisms as well as understand the potential health effects of particle-bound oxidative species, the alpha-pinene-O(3) oxidation chemical system was studied to elucidate the structures of reaction products using liquid chromatography-multiple stage mass spectrometry (LC-MS(n)). The classes of compounds identified based on their multiple stage-MS fragmentation patterns, mechanistic considerations of alpha-pinene-O(3) oxidation, and general fragmentation rules, of the products from this reaction system were highly oxygenated species, predominantly containing hydroperoxide and peroxide functional groups. The oxidant species observed were clearly stable for the 1-3 h that elapsed during aerosol collection and analysis, and probably for much longer, thus rendering it possible for these species to bind onto particles forming fine particulate organic peroxides that concentrate on the particles and could deliver concentrated doses of ROS in vivo to tissue.

Identification of organic hydroperoxides and peroxy acids using atmospheric pressure chemical ionization–tandem mass spectrometry (APCI-MS/MS): application to secondary organic aerosol

“…Second, the full-scan mass spectrum (Fig. 5a) shows the presence of monomer (m/z = 80-250), dimer (m/z = 250-450) and trimer (m/z = 450-600) species, as has been reported in previous work (Venkatachari and Hopke, 2008). Third, and perhaps most importantly, the 51 Da neutral loss scan (Fig.…”

Identification of Organic Hydroperoxides and Peroxy Acids Using Atmospheric Pressure Chemical Ionization – Tandem Mass Spectrometry (APCI-MS/MS): Application to Secondary Organic Aerosol

“…Second, the full scan mass spectrum (Fig. 5 (A)) shows the presence of monomer (m/z=80-250), dimer (m/z=250-450) and trimer (m/z=450-600) species, as has been reported in previous work (Venkatachari and Hopke, 2008). Third, and perhaps most importantly, the 51 Da neutral loss scan (Fig.…”

A New Aerosol Flow System for Photochemical and Thermal Studies of Tropospheric Aerosols

“…Reactions of α-pinene have served as a model system for SOA formation in numerous studies (e.g., see Jaoui and Kamens 2001;Kamens and Jaoui 2001;Bonn and Moortgat 2002;Bröske et al 2003;Baltensperger et al 2005;Lee and Kamens 2005;Tolocka et al 2006;Bonn et al 2007;Offenberg et al 2007;Venkatachari and Hopke 2008;Yu et al 2008), and thus was used here to demonstrate the capabilities of the new flow system. SOA formation is shown here from two separate reaction systems, the NO x photooxidation of α-pinene and the ozonolysis of α-pinene.…”