Development of negative-ion proton-transfer chemical-ionization mass spectrometry (NI-PT-CIMS) for the measurement of gas-phase organic acids in the atmosphere

2008 ◽  
Vol 274 (1-3) ◽  
pp. 48-55 ◽  
Author(s):  
Patrick Veres ◽  
James M. Roberts ◽  
Carsten Warneke ◽  
Daniel Welsh-Bon ◽  
Mark Zahniser ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Proton Transfer ◽  
Organic Acids ◽  
Gas Phase ◽  
Chemical Ionization ◽  
Negative Ion ◽  
Ionization Mass Spectrometry ◽  
Chemical Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Ion Proton

scholarly journals Chemistry of α-pinene and naphthalene oxidation products generated in a Potential Aerosol Mass (PAM) chamber as measured by acetate chemical ionization mass spectrometry

2014 ◽  
Vol 7 (7) ◽  
pp. 6385-6429 ◽  
Author(s):  
P. S. Chhabra ◽  
A. T. Lambe ◽  
M. R. Canagaratna ◽  
H. Stark ◽  
J. T. Jayne ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Organic Acids ◽  
Gas Phase ◽  
Chemical Ionization ◽  
Oxidation Products ◽  
Ionization Mass Spectrometry ◽  
Chemical Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Aerosol Formation ◽  
Ion Chemistry

Abstract. Recent developments in high resolution, time-of-flight chemical ionization mass spectrometry (HR-ToF-CIMS) have made possible the direct detection of atmospheric organic compounds in real-time with high sensitivity and with little or no fragmentation, including low volatility, highly oxygenated organic vapors that are precursors to secondary organic aerosol formation. Here, for the first time, we examine gas-phase O3 and OH oxidation products of α-pinene and naphthalene formed in the PAM flow reactor with an HR-ToF-CIMS using acetate reagent ion chemistry. Integrated OH exposures ranged from 1.2 × 1011 to 9.7 × 1011 molec cm−3 s, corresponding to approximately 1.0 to 7.5 days of equivalent atmospheric oxidation. Measured gas-phase organic acids are similar to those previously observed in environmental chamber studies. For both precursors, we find that acetate-CIMS spectra capture both functionalization (oxygen addition) and fragmentation (carbon loss) as a function of OH exposure. The level of fragmentation is observed to increase with increased oxidation. We present a method that estimates vapor pressures of organic molecules using the measured O/C ratio, H/C ratio, and carbon number for each compound detected by the CIMS. The predicted condensed-phase SOA average acid yields and O/C and H/C ratios agree within uncertainties with previous AMS measurements and ambient CIMS results. While acetate reagent ion chemistry is used to selectively measure organic acids, in principle this method can be applied to additional reagent ion chemistries depending on the application.

scholarly journals Real-time measurements of gas-phase organic acids using SF<sub>6</sub><sup>−</sup> chemical ionization mass spectrometry

2018 ◽  
Vol 11 (9) ◽  
pp. 5087-5104 ◽  
Author(s):  
Theodora Nah ◽  
Yi Ji ◽  
David J. Tanner ◽  
Hongyu Guo ◽  
Amy P. Sullivan ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Organic Acids ◽  
Organic Acid ◽  
Real Time ◽  
Gas Phase ◽  
Chemical Ionization ◽  
Ionization Mass Spectrometry ◽  
Chemical Ionization Mass Spectrometry ◽  
Rural Site ◽  
Ionization Mass

Abstract. The sources and atmospheric chemistry of gas-phase organic acids are currently poorly understood, due in part to the limited range of measurement techniques available. In this work, we evaluated the use of SF6- as a sensitive and selective chemical ionization reagent ion for real-time measurements of gas-phase organic acids. Field measurements are made using chemical ionization mass spectrometry (CIMS) at a rural site in Yorkville, Georgia, from September to October 2016 to investigate the capability of this measurement technique. Our measurements demonstrate that SF6- can be used to measure a range of organic acids in the atmosphere. One-hour averaged ambient concentrations of organic acids ranged from a few parts per trillion by volume (ppt) to several parts per billion by volume (ppb). All the organic acids displayed similar strong diurnal behaviors, reaching maximum concentrations between 17:00 and 19:00 EDT. The organic acid concentrations are dependent on ambient temperature, with higher organic acid concentrations being measured during warmer periods.

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