Fractionation and characterization of dissolved organic matter (DOM) in refinery wastewater by revised phase retention and ion-exchange adsorption solid phase extraction followed by ESI FT-ICR MS

Zhi Fang; Chen He; Yongyong Li; Keng H Chung; Chunming Xu; Quan Shi

doi:10.1016/j.talanta.2016.10.064

Fractionation and characterization of dissolved organic matter (DOM) in refinery wastewater by revised phase retention and ion-exchange adsorption solid phase extraction followed by ESI FT-ICR MS

Talanta. 2017 Jan 1:162:466-473. doi: 10.1016/j.talanta.2016.10.064. Epub 2016 Oct 18.

Authors

Zhi Fang¹, Chen He¹, Yongyong Li², Keng H Chung³, Chunming Xu¹, Quan Shi⁴

Affiliations

¹ State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China.
² State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China; School of Marine Science, Ningbo University, Ningbo, Zhejiang 315211, China.
³ Liaoning Huajin Tongda Chemicals Co. Ltd., Panjin, Liaoning 124000, China.
⁴ State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China. Electronic address: sq@cup.edu.cn.

PMID: 27837858
DOI: 10.1016/j.talanta.2016.10.064

Abstract

Although the progress of high resolution mass spectrometry in the past decade has enabled the molecular characterization of dissolved organic matter (DOM) in water as a whole, fractionation of DOM is necessary for a comprehensive characterization due to its super-complex nature. Here we proposed a method for the fractionation of DOM in a wastewater based on solubility and acidic-basic properties. Solid phase extraction (SPE) cartridges with reversed phase retention and ion-exchange adsorption capacities, namely MAX and MCX, were used in succession to fractionate a petroleum refinery wastewater into four fractions: hydrophobic acid (HOA), hydrophobic neutral (HON), hydrophobic base (HOB), and hydrophilic substance (HIS) fractions. According to the total organic carbon (TOC) analysis, 72.6% (in term of TOC) of DOM was extracted in hydrophobic fractions, in which HON was the most abundant. Hydrophobic extracts were characterized by negative and positive ion electrospray (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), respectively. Compounds with multiple oxygen atoms were predominant in the HOA, which were responded strongly in the negative ESI MS. Nitrogen containing compounds were the major detected species by positive ion ESI in all hydrophobic fractions. The molecular composition of the DOM were discussed based on the FT-ICR MS results. The fractionation provided salt free samples which enables the direct analysis of the fractions by ESI and a deep insight into the molecular composition of DOM in the wastewater. The method is potential for routine evaluation of DOM in industry wastewaters, as well as environmental water samples.

Keywords: Dissolved organic matter; ESI; FT-ICR MS; MAX; MCX; SPE.