Ambient measurements of amines, related nitrogen-containing compounds and other organic compounds in air using chemical ionization high-resolution mass spectrometry
Authors
Harald Stark — Aerodyne Research, Inc.
John B Nowak — Aerodyne Research, Inc.
Aroob Abdelhamid — University of Colorado
Eleanor Browne — University of Colorado
Joel K Kimmel — Aerodyne Research, Inc./Tofwerk
Roy Leon Mauldin — University of Colorado, Boulder
James Smith — University of California, Irvine
Rod Soper — Southern Great Plains
John R Schatz — ARM Climate Research Facility
John T Jayne — Aerodyne Research, Inc.
Jordan Krechmer — Aerodyne Research, Inc.
Douglas R Worsnop — Aerodyne Research, Inc.
Category
Secondary organic aerosol
Description
Developments in chemical ionization mass spectrometry (CIMS) have dramatically enanced detection of gas and aerosol species in the atmopsherie, leading to a “molecular revolution” in our understanding of photochemical processes underlying secondary aerosol formation and growth. Examples include nitrate anion clustering detection of high oxidized orgnaics, so-called “HOMS”; iodide anion clastering of a broad range of oxidized oregnaincs (oVOCs); and, recently, enhanced proton transfer (PTR) detection of a range of VOCs and oVOCs. We will present an overview of recent CIMS applications.
A specfic example is measurement of ammonia and amines, which are important atmospheric constituents that originate from biogenic and anthropogenic processes. Their tropospheric mixing ratios can be very low, often in the sub-pptv levels. Even at these extremely low levels, they can be important for atmospheric nucleation processes, often as basic counterparts to sulfuric acid. In a DoE sponsored SBIR project, we developed an ethanol-CIMS technique that uses chemical ionization by protonated ethanol ions and detection by a a high-resolution time-of-flight mass spectrometer. We present field measurements from the HISCALE campaign that took place at the ARM-SGP site in Billings, Oklahoma, in August and September of 2016. We report measurements of ammonia, amines, amides, imides, urea and other reduced nitrogen-containing compounds with ethanol-CIMS.
As with other recent CIMS application, time resolution and detection limits of this instrument are improved compared to previously used techniques. Further, the high-resolution mass spectra allow formula assignment to ions related to new compounds that have not been known to exist in the atmosphere and investigate their temporal behavior.
This work was supported by Award No. DE-SC0011218.
