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RESEARCH ARTICLE

Molecular characterisation of ambient aerosols by sequential solvent extractions and high-resolution mass spectrometry

Jingyi Zhang A B , Bin Jiang A C , Zhiheng Wang A , Yongmei Liang A D , Yahe Zhang A , Chunming Xu A and Quan Shi A D
+ Author Affiliations
- Author Affiliations

A State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China.

B Patent Examination Cooperation Centre of the Patent Office, State Intellectual Property Office (SIPO), Guangzhou 510530, China.

C State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou 510640, China.

D Corresponding authors. Email: ymliang@cup.edu.cn; sq@cup.edu.cn

Environmental Chemistry 15(3) 150-161 https://doi.org/10.1071/EN17197
Submitted: 6 November 2017  Accepted: 14 February 2018   Published: 31 May 2018

Environmental context. Organic compounds generally make a large contribution to ambient aerosol fine particles, and can influence atmospheric chemistry. Solvent extraction before mass spectrometry is widely used for the determination of organic compounds in aerosols, but the molecular selectivity of different solvents is unclear. We extracted an aerosol sample with various solvents and show how the organic compound profile obtained by mass spectrometry changes depending on the extracting solvent.

Abstract. For a comprehensive characterisation of organic compounds in aerosols, samples collected on a hazy day from Beijing were sequentially extracted with various solvents and analysed by Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Electrospray ionisation (ESI) was used for the MS analysis. Aerosol samples were extracted in an apolar-to-polar solvent order of n-hexane (n-C6), dichloromethane (DCM), acetonitrile (ACN) and water, and also extracted in reverse sequence. The separated fractions were defined as non-polar, low-polarity, mid-polarity and high-polarity organic compounds respectively. Approximately 70 % of the total organic carbon (TOC) was extractable, of which the water-soluble organic carbon (WSOC) and non-polar organic carbon accounted for 30 and 25 % of the TOC respectively. Non-polar and low-polarity compounds with a high degree of molecular condensation such as oxidised polycyclic aromatic hydrocarbons (PAHs) and nitrogen-containing compounds (CHN) were extracted by n-C6 and DCM. Water-soluble organic matter (WSOM) was predominant with aliphatic and aromatic organosulfates (CHOS) and nitrooxy-organosulfates (CHONS). Most oxygen-containing compounds (CHO) and oxygen- and nitrogen-containing compounds (CHON) with high double-bond equivalents (DBEs) and long carbon chains tended to be extracted into organic solvents.

Additional keywords: molecular sensitivity, organic compounds, organosulfates.


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