| Title: | Using collision-induced dissociation to constrain sensitivity of ammonia chemical ionization mass spectrometry ( NH4+ CIMS) to oxygenated volatile organic compounds |
| Author(s): | Zaytsev A; Breitenlechner M; Koss AR; Lim CY; Rowe JC; Kroll JH; Keutsch FN; |
| Address: | "John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA. Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA. Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA" |
| ISSN/ISBN: | 1867-1381 (Print) 1867-8548 (Electronic) 1867-1381 (Linking) |
| Abstract: | "Chemical ionization mass spectrometry (CIMS) instruments routinely detect hundreds of oxidized organic compounds in the atmosphere. A major limitation of these instruments is the uncertainty in their sensitivity to many of the detected ions. We describe the development of a new high-resolution time-of-flight chemical ionization mass spectrometer that operates in one of two ionization modes: using either ammonium ion ligand-switching reactions such as for NH4+ CIMS or proton transfer reactions such as for protontransfer-reaction mass spectrometer (PTR-MS). Switching between the modes can be done within 2min. The NH4+ CIMS mode of the new instrument has sensitivities of up to 67 000 dcps ppbv(-1) (duty-cycle-corrected ion counts per second per part per billion by volume) and detection limits between 1 and 60 pptv at 2sigma for a 1 s integration time for numerous oxygenated volatile organic compounds. We present a mass spectrometric voltage scanning procedure based on collision-induced dissociation that allows us to determine the stability of ammonium-organic ions detected by the NH4+ CIMS instrument. Using this procedure, we can effectively constrain the sensitivity of the ammonia chemical ionization mass spectrometer to a wide range of detected oxidized volatile organic compounds for which no calibration standards exist. We demonstrate the application of this procedure by quantifying the composition of secondary organic aerosols in a series of laboratory experiments" |
| Notes: | "PubMed-not-MEDLINEZaytsev, Alexander Breitenlechner, Martin Koss, Abigail R Lim, Christopher Y Rowe, James C Kroll, Jesse H Keutsch, Frank N eng P42 ES027707/ES/NIEHS NIH HHS/ Germany 2019/01/01 Atmos Meas Tech. 2019; 12(3):1861-1870. doi: 10.5194/amt-12-1861-2019. Epub 2019 Mar 20" |
