Preprints
https://doi.org/10.5194/amt-2022-147
https://doi.org/10.5194/amt-2022-147
 
28 Jun 2022
28 Jun 2022
Status: this preprint is currently under review for the journal AMT.

Realtime measurement of phase partitioning of organic compounds using a Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer coupled to a CHARON inlet

Yarong Peng1,2, Hongli Wang2, Yaqin Gao2, Shengao Jing2, Shuhui Zhu2, Dandan Huang2, Peizhi Hao3, Shengrong Lou2, Tiantao Cheng4,5, Cheng Huang2, and Xuan Zhang3 Yarong Peng et al.
  • 1Department of Environmental Science and Engineering, Fudan University, Shanghai, 200438, China
  • 2State Environmental Protection Key Laboratory of Formation and Prevention of Urban Air Pollution Complex, Shanghai Academy of Environmental Sciences, Shanghai, 200233, China
  • 3School of Natural Sciences, University of California, Merced, 95343, USA
  • 4Department of Atmospheric and Oceanic Sciences, Fudan University, Shanghai, 200438, China
  • 5Big Data Institute for Carbon Emission and Environmental Pollution, Fudan University, Shanghai, 200438, China

Abstract. Understanding the gas-particle partitioning of semivolatile organic compounds (SVOCs) is of crucial importance in the accurate representation of the global budget of atmospheric organic aerosols. In this study, we quantified the gas- vs. particle-phase fractions of a large number of SVOCs in real time in an urban area of East China with the use of a CHemical Analysis of aeRosols ONline (CHARON) inlet coupled to a high resolution Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-ToF-MS). We demonstrated the use of the CHARON inlet for highly efficient collection of particulate SVOCs while maintaining the intact molecular structures of these compounds. The collected month-long dataset with hourly resolution allows us to examine the gas-particle partitioning behaviors of a variety of SVOCs under different ambient conditions. By comparing the measurements with model predictions using the instantaneous equilibrium partitioning theory, we found that the dissociation of large parent molecules during the PTR ionization process likely introduces large uncertainties to the measured gas- vs. particle-phase fractions of less oxidized SVOCs, and therefore, caution should be taken when linking the molecular composition to the particle volatility when interpreting the PTR-ToF-MS data. Our analysis suggests that understanding the fragmentation mechanism of oxidized SVOCs and accounting for the neutral losses of small moieties during the molecular feature extraction from the raw mass spectra could reduce, to a large extent, the uncertainties associated with the gas-particle partitioning measurement of SVOCs in the ambient atmosphere.

Yarong Peng et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on amt-2022-147', Anonymous Referee #2, 22 Jul 2022
  • RC2: 'Comment on amt-2022-147', Anonymous Referee #1, 10 Aug 2022

Yarong Peng et al.

Yarong Peng et al.

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Short summary
This work examined the phase partitioning behaviors of organic compounds at hourly resolution in ambient with the use of the CHemical Analysis of aeRosols ONline (CHARON) inlet coupled to a Proton Transfer Reaction Time-of-Flight Mass Spectrometry (PTR-ToF-MS). We found that properly accounting for the neutral losses of small moieties during the molecular feature extraction from PTR mass spectra could significantly reduce uncertainties associated with the gas-particle partitioning measurements.