AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
A New Direct Bromide Anion Chemical Ionization Mass Spectrometry (Br-CIMS) Technique for the Measurement of HO2
JAVIER SANCHEZ, Dexian Chen, David Tanner, Greg Huey, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 185 Working Group: Instrumentation and Methods
Abstract Hydroperoxy radicals (HO2) play an important role in secondary organic aerosol (SOA) formation. Despite their importance, laboratory chamber experiments designed to understand SOA formation do not routinely measure HO2. The lack of HO2 measurements restricts the applicability of chamber experiments to the real atmosphere. HO2 are not routinely measured due to the difficulty associated with the measurements as well as the need for additional instrumentation. In this work, we evaluated a number of reagent ions for the detection of HO2 using chemical ionization mass spectrometry and present a new direct bromide anion chemical ionization mass spectrometric (Br-CIMS) technique for the detection of HO2. The direct nature of the technique eliminates the need for chemical titration with NO, which sidesteps artifacts contributed by organic peroxy radicals. The technique has a sensitivity of 4.95 Hz/ppt with a 0.7 ppt detection limit for 1 minute integration times. Ambient data collected in Atlanta demonstrates high selectivity towards HO2 at mass-to-charge 112, suggesting that high resolution instrumentation is not necessary for obtaining accurate HO2 measurements. The technique is applicable to both laboratory and ambient sampling and aims to exploit the increasing popularity of CIMS to improve the atmospheric relevance of laboratory chamber experiments. Ambient data collected in Atlanta and laboratory applications will be presented to showcase the usefulness of the technique.