Online molecular characterisation of organic aerosols in an atmospheric chamber using extractive electrospray ionisation mass spectrometry

Gallimore, Peter J. and Giorio, Chiara and Mahon, Brendan M. and Kalberer, Markus. (2017) Online molecular characterisation of organic aerosols in an atmospheric chamber using extractive electrospray ionisation mass spectrometry. Atmospheric Chemistry and Physics, 17 (23). pp. 14485-14500.

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Official URL: https://edoc.unibas.ch/81350/

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The oxidation of biogenic volatile organic compounds (VOCs) represents a substantial source of secondary organic aerosol (SOA) in the atmosphere. In this study, we present online measurements of the molecular constituents formed in the gas and aerosol phases during alpha-pinene oxidation in the Cambridge Atmospheric Simulation Chamber (CASC). We focus on characterising the performance of extractive electrospray ionisation (EESI) mass spectrometry (MS) for particle analysis. A number of new aspects of EESI-MS performance are considered here. We show that relative quantification of organic analytes can be achieved in mixed organic-inorganic particles. A comprehensive assignment of mass spectra for alpha-pinene derived SOA in both positive and negative ion modes is obtained using an ultra-high-resolution mass spectrometer. We compare these online spectra to conventional offline ESI-MS spectra and find good agreement in terms of the compounds identified, without the need for complex sample work-up procedures. Under our experimental conditions, EESI-MS signals arise only from particle-phase analytes. High-time-resolution (7 min) EESI-MS spectra are compared with simulations from the near-explicit Master Chemical Mechanism (MCM) for a range of reaction conditions. We show that MS peak abundances scale with modelled concentrations for condensable products (pinonic acid, pinic acid, OH-pinonic acid). Relative quantification is achieved throughout SOA formation as the composition, size and mass (5-2400 mu g m(-3)) of particles is evolving. This work provides a robust demonstration of the advantages of EESI-MS for chamber studies over offline ESI-MS (time resolution, relative quantification) and over "hard" online techniques (molecular information).
Faculties and Departments:05 Faculty of Science > Departement Umweltwissenschaften > Geowissenschaften > Atmospheric Sciences (Kalberer)
UniBasel Contributors:Kalberer, Markus
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:European Geosciences Union
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:13 Apr 2021 09:15
Deposited On:13 Apr 2021 09:15

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