AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Analysis of Polar Organic Compounds by TAG-AMS: Case Study of an Alpine Valley in France
AMELIE BERTRAND, H. Langley DeWitt, Brice Temime-Roussel, Thorsten Hohaus, Donna Sueper, Florie Chevrier, Jean-Luc Besombes, Jean-Luc Jaffrezo, Grisa Mocnik, Nathan Kreisberg, Gabriel Isaacman, Susanne Hering, Allen H. Goldstein, John Jayne, Henri Wortham, Nicolas Marchand, Aix-Marseille Université, CNRS, LCE FRE 3416
Abstract Number: 239 Working Group: Source Apportionment
Abstract Highly time-resolved measurements of organic markers in ambient aerosol represent a keystone for our understanding of the evolution and the source of the Organic Aerosol (OA) in the atmosphere. A new in situ Thermal Desorption Aerosol Gas Chromatograph (TAG) coupled with an Aerosol Mass Spectrometer (TAG-AMS) has thus been developed to bridge the gap between classical offline organic markers analysis and online bulk OA analysis (William et al, 2014). The TAG system as described by Williams et al. (2006) allows for the online analysis of non or moderate polar organic markers, such as PAHs, alkanes, or hopanes, but is limited at measuring very polar organic markers such as levoglucosan. An in situ derivatization step has then been developed by flushing MSTFA saturated helium through the system during thermo-desorption (Isaacman et al., 2014). Thus the combined TAG-AMS system with in-situ derivatization provides real-time detection by AMS offering quantitative mass loadings data while simultaneously contributing molecular scale information at a high time resolution for detailed organic speciation of polar and unpolar SOA compounds.
The TAG-AMS was deployed on site in the Arve Valley (France) in February 2014 for an intensive two-week campaign co-located with a set of instrumentation such as PTR-ToF-MS, Aethalometer AE33, SMPS and HV samplers. The system was operated in AMS mode for 60 minutes during which aerosols were sampled in the TAG collection cell at 6.7 L/min. TAG was operated for desorption and subsequent analysis during 40 minutes. In addition an extra HV sampler was operated on the same schedule as the TAG.
Direct comparisons of online data are made to offline techniques. Source apportionment for both data sets (AMS and TAG) was performed using a PMF model and is compared to the Aethalometer results. Finally challenges with the derivatization step and ensued optimisations made are presented.