Laser desorption/ionization mass spectrometric stu

Authors: Mingqiang Huang Weijun Zhang Liqing Hao Zhenya Wang Wenwu Zhao Xuejun Gu Xiaoyong Guo Xianyun Liu Bo Long Li Fang

Publish Date: 2007/12/13

Volume: 58, Issue: 3, Pages: 237-252

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Abstract

Five aromatic hydrocarbons – benzene toluene ethylbenzene pxylene and 124trimethylbenzene – were selected to investigate the laser desorption/ionization mass spectra of secondary organic aerosols SOA resulting from OHinitiated photooxidation of aromatic compounds The experiments were conducted by irradiating aromatic hydrocarbon/CH3ONO/NO X mixtures in a homemade smog chamber The aerosol timeofflight mass spectrometer ATOFMS was used to measure the aerodynamic size and chemical composition of individual secondary organic aerosol particles in realtime Experimental results showed that aerosol created by aromatics photooxidation is predominantly in the form of fine particles which have diameters less than 25 μm ie PM25 and different aromatic hydrocarbons SOA mass spectra have eight same positive laser desorption/ionization mass spectra peaks m/z = 18 29 43 44 46 57 67 77 These mass spectra peaks may come from the fragment ions of the SOA products oxocarboxylic acids aldehydes and ketones nitrogenated organic compounds furanoid and aromatic compounds The possible reaction mechanisms leading to these products were also discussed

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