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Title: Revisiting benzene cluster cations for the chemical ionization of dimethyl sulfide and select volatile organic compounds

Here, benzene cluster cations were revisited as a sensitive and selective reagent ion for the chemical ionization of dimethyl sulfide (DMS) and a select group of volatile organic compounds (VOCs). Laboratory characterization was performed using both a new set of compounds (i.e., DMS, β-caryophyllene) as well as previously studied VOCs (i.e., isoprene, α-pinene). Using a field deployable chemical-ionization time-of-flight mass spectrometer (CI-ToFMS), benzene cluster cations demonstrated high sensitivity (> 1 ncps ppt−1) to DMS, isoprene, and α-pinene standards. Parallel measurements conducted using a chemical-ionization quadrupole mass spectrometer, with a much weaker electric field, demonstrated that ion–molecule reactions likely proceed through a combination of ligand-switching and direct charge transfer mechanisms. Laboratory tests suggest that benzene cluster cations may be suitable for the selective ionization of sesquiterpenes, where minimal fragmentation (< 25 %) was observed for the detection of β-caryophyllene, a bicyclic sesquiterpene. The in-field stability of benzene cluster cations using CI-ToFMS was examined in the marine boundary layer during the High Wind Gas Exchange Study (HiWinGS). The use of benzene cluster cation chemistry for the selective detection of DMS was validated against an atmospheric pressure ionization mass spectrometer, where measurements from the two instruments were highly correlated (R2 > 0.95, 10 s averages)more » over a wide range of sampling conditions.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7]
  1. Univ. of California San Diego, La Jolla, CA (United States); California Institute of Technology, Pasadena, CA (United States)
  2. Univ. of California San Diego, La Jolla, CA (United States); California Polytechnic State Univ., San Luis Obispo, CA (United States)
  3. Univ. of California San Diego, La Jolla, CA, (United States)
  4. Univ. of California San Diego, La Jolla, CA (United States); Georgia Gwinnett College, Lawrenceville, GA (United States)
  5. Univ. of Colorado, Boulder, CO (United States)
  6. Univ. of Hawaii, Manoa, Honolulu, HI (United States)
  7. Univ. of California San Diego, La Jolla, CA (United States); Univ. of Wisconsin-Madison, Madison, WI (United States)
Publication Date:
OSTI Identifier:
1245498
Grant/Contract Number:
SC0006431
Type:
Published Article
Journal Name:
Atmospheric Measurement Techniques (Online)
Additional Journal Information:
Journal Name: Atmospheric Measurement Techniques (Online); Journal Volume: 9; Journal Issue: 4; Journal ID: ISSN 1867-8548
Publisher:
European Geosciences Union
Research Org:
Univ. of California, San Diego, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY