Use of Comprehensive Two-Dimensional Gas Chromatography/Time-of-Flight Mass Spectrometry for the Characterization of Biodegradation and Aromatic Hydrocarbons in Petroleum

Abstract

A comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC-TOFMS) method has been developed for separation of a series of petroleum. Crude oils in different biodegradation level were selected from Hala'alate Mountains to allow an assessment of biodegradation and characterization of aromatic hydrocarbons. The increased resolution and separation afforded by the GC×GC technique provides more complete compositional information on complex biodegraded oil samples than one-dimentional GC, and improves the ability to study biodegradation trends. Containing abundant geochemical and petroleum geology information as saturates, aromatics can't be ignored in organic geochemistry research. Most of routine source rocks and crude oils are dominated by bicyclic and tricyclic aromatics. Oils in study area has subjected to series events, particularly biodegradation, which has great effect on the molecular composition and physical properties of crude oils. On the other hand, former studies indicated that aromatic unresolved complex mixtures (UCMs) consisted in part of alkylaromatics such as alkyltetralins and alkylindanes. Under certain conditions, micro-organisms metabolise various classes of compounds present in oil, which results in the decrease and disappearance of the dominant aliphatic and aromatics components of petroleum and in the development of UCMs, referred to as a big “hump” in GC. Compared to GC×GC, traditional 1D GC and GC/MS are limited to gross overall shapes and abundance of unresolved bands, laboratory results from this study demonstrate that GC×GC/TOFMS can be a powerful means of examining oils and study biodegradation trends. Due to the large number of compounds presents in oils, it is impossible to discuss all classes of compounds present in the UCM. Some aromatic class compounds were selected in order to fully explore the chemical composition and biodegradation trend. The GC×GC/TOFMS method developed in this study represents a step in the direction of resolving and identifying the specific classes of compounds present in the aromatic UCMs. Further work will be directed towards quantifying individual components and classes of compounds in order to make insight in aromatic UCMs.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015