Laboratory and Field Investigations of Gas/Aerosol Partitioning of Amine Aerosols Using FIGAERO/HRToF-CIMS
Monday, 15 December 2014
Despite low ambient concentrations, amines are believed to play important roles in aerosol formation and growth and have significant impacts on aerosol hygroscopicity. HRToF-CIMS equipped with a Filter Inlet for Gases and AEROsols (FIGAERO) was utilized to investigate the gas/aerosol partitioning of amines (e.g., methylamine, C2-amines, C3-amines, and C4-amines) under controlled laboratory and ambient conditions. Aerosol samples were collected onto a 25 mm diameter PTFE filter with a pore size of 0.5 μm, followed by thermal desorption (up to 200°C) and analysis by HRToF-CIMS. Aerosol collection and desorption efficiencies were characterized with atomized ammonia and aminium salts. The calibration curve of (CH3NH3)2SO4 was produced over a range of concentrations of interest and showed linear response. During ambient measurement, ammonia was found mostly in the gas phase. However, all amines including their oxidation products (e.g. CH2NH) were mostly in the aerosol phase. The gas/aerosol partitioning of laboratory generated NH4NO3 and (CH3NH3)2SO4 were studied at various RH and were compared with E-AIM model simulations to evaluate the performance of the FIGAERO/HRToF-CIMS.