Acidic and Neutral Polar NSO Compounds in Heavily Biodegraded Oils Characterized by Negative-Ion ESI FT-ICR MS
Acidic and Neutral Polar NSO Compounds in Heavily Biodegraded Oils Characterized by Negative-Ion ESI FT-ICR MS
Yinhua Pan, Yuhong Liao*, Quan Shi, and Chang Samuel Hsu
The State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou 510640, P. R. China
University of Chinese Academy of Sciences, Beijing 100049, China
State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102200, China d (a) Petro Bio Oil Consulting, Tallahassee, FL 32312
Department of Chemical and Biomedical Engineering, Florida State University Tallahassee, Florida 32310, United States of America
Corresponding Author: *Telephone: +862085291567. Fax: +862085290706. Email address: liaoyh@gig.ac.cn
DOI: 10.1021/ef400191h
Keywords: Aromatic compounds; Biodegradation; Hydrocarbons; Lipids; Petrochemicals
Abstract: Five heavily biodegraded tar sand bitumens from an oil column were separated into maltene and asphaltene fractions for analysis by negativeion electrospray (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS). These bitumens have identical source, which have experienced a natural sequence of biodegradation. The polar NSO compounds in maltene fractions contain O1, S1O1, O2, S1O2, S2O2, O3, S1O3, O4, S1O4, N1, N1O1, N1O2, N1S1 and S1 classes; while the polar NSO compounds in asphaltene fractions contain O1, S1O1, S2O1, O2, S1O2, S2O2, O3, S1O3, S2O3, O4, S1O4, S2O4, O5, S1O5, S2O5, O6, N1, N1O1, N1O2, N1O3, N1S1 and N2 classes. Polar NSO compounds with stronger molecular polarity and larger molecular weight are readily fractionated into asphaltene fractions. The O2 class is prevalent in polar NSO compounds of both maltene and asphaltene fractions of all bitumen samples. The N1 class in maltene fractions is dominated by compounds with DBE values of 9, 10, 12 and 13, while N1 class in asphaltene fractions is dominated by compounds with DBE of 15. Most of these N1 compounds are likely pyrrolic compounds with various numbers of aromatic rings. The biodegradation pathways of nitrogencontaining compounds are also explored in this study. N1 species are likely converted to N1O1 and N1O2 species following biodegradation pathways as ringopening reaction or carbazole dioxygenase (CARDO) catalytic oxidation reaction. S1O2-5 classes are identified as the dominant sulfurcontaining compound classes under negativeion ESI mode. These classes are considered to contain acid functionalities with higher polarity because the sulfurcontaining compounds without oxygen are difficult to analyze by negativeion ESI in which acids can be ionized by deprotonation. Both progressive oxidation and sulfuration may be involved in the anaerobic biodegradation of sulfurcontaining acidic compounds.