10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Automated Organic Aerosol Measurement with Quartz Filter-based Thermal Desorption Gas Chromatography Mass Spectrometry (TAG)
HAIXIA REN, Mo Xue, Zhaojin An, Wei Zhou, Jingkun Jiang, Tsinghua University, Beijing, 100084, China
Abstract Number: 465 Working Group: Aerosol Chemistry
Abstract Rapid characterization and high chemical resolution of organic compounds in atmospheric particulate matter are required in aerosol research, especially when revealing the sources of primary organic aerosol, the formation of secondary organic aerosol and atmospheric evolution of organic aerosol. Real-time characterization is preferable considering the variation and lability of organic aerosol, although it can be very challenging due to the chemical complexity of aerosol, especially characterization at molecular level. In-situ thermal desorption aerosol gas chromatography (TAG) was previously developed to characterize organics in aerosols at molecular level. Briefly, aerosols are collected in a collection cell, then organics in aerosols are thermally vaporized and captured in a cooled trap, finally injected into gas chromatograph (GC) for analysis. However, previously reported either stainless steel impactor or metal-fiber filter based TAG has high risk of residue accumulation, especially under severe particulate matter loading that is frequently encountered in polluted atmospheric environment.
In this study, a quartz filter based TAG, which can be readily disassembled and allows filter replacement, has been developed and evaluated using C7-C40 n-alkanes. The developed device is composed of a quartz filter collection cell, temperature and pressure control system, and combined with commercial gas chromatography mass spectrometry (GCMS) for evaluation. The thermally desorbed organics were trapped by the analytical column. C11-C40 with boiling point from 196 – 525°C was detected with residues of less than 1% and demonstrated repeatability of less than 10% except for C11, C12, and C40. Considering the complexity of organic aerosol, the device was hyphenated with two dimensional gas chromatography (GC´GC-MS) for analysis, and the analytical performance was validated by alkanes, polycyclic aromatic hydrocarbons, sterols, acids, etc. The developed instrument was deployed for hourly in-situ organic compounds analysis of ambient PM2.5 in Beijing, and organic aerosol emissions from residential solid fuel combustion. Results from these field studies will be discussed.