Real-time measurement of phase partitioning of organic compounds using a proton-transfer-reaction time-of-flight mass spectrometer coupled to a CHARON inlet
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 ti...
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Published in | Atmospheric measurement techniques Vol. 16; no. 1; pp. 15 - 28 |
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Main Authors | , , , , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Katlenburg-Lindau
Copernicus GmbH
04.01.2023
Copernicus Publications |
Subjects | |
Online Access | Get full text |
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Summary: | 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 of
a variety of SVOCs under ambient conditions. By comparing the measurements
with model predictions using 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 SVOCs and
accounting for the neutral losses of small moieties during the molecular
feature extraction from the raw PTR mass spectra could reduce, to a large
extent, the uncertainties associated with the gas–particle partitioning
measurement of SVOCs in the ambient atmosphere. |
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ISSN: | 1867-8548 1867-1381 1867-8548 |
DOI: | 10.5194/amt-16-15-2023 |