Identification of Alkylbenzenes and Direct Determination of BTEX and BTEX + C3-Benzenes in Oils by GC/MS

Abstract

A rapid, reliable, and effective method for direct determination of benzene, toluene, ethylbenzene, and o-, m-, and p-xylenes (BTEX) and alkyl-substituted benzene components in oil has been developed using GC/MS in selected ion monitoring mode. Using this method, 58 alkyl-substituted benzene components in a light crude oil, Alberta Sweet Mixed Blend, were positively identified, and the concentrations of the individual BTEX compounds and C3-benzene isomers in over 200 different crude and weathered oils were quantified. The effects of weathering on compositional changes of alkylbenzenes were also studied. The plots of the concentrations of BTEX and BTEX + C3-benzenes versus weathering percentages can be used to estimate the weathering extent of weathered oil samples, especially for those short-term weathered oils for which the loss of BTEX and C3-benzenes is significant For environmental and toxicity concerns, BTEX levels in oil are a very important parameter. BTEX is the collective name of benzene, toluene, ethylbenzene, and the xylene isomers (p-, m-, and o-xylenes). BTEX compounds are the most common aromatic compounds in petroleum (the amount of BTEX can be up to a few percent of the total weight for some crude oils) and often occur in greater amounts than other aromatics. BTEXs constitute the most soluble, most mobile fraction of crude oil and many petroleum products. BTEXs have many chemical applications and are widely used in the manufacture of paints, synthetic rubber, agricultural chemicals, and chemical intermediates. The concentration of BTEX in petroleum can directly affect the physical and chemical properties of petroleum such as density, viscosity, flash points, dispersibility, emulsion stability, solubility, and weathering processes. On the other hand, BTEX compounds frequently enter soil, sediments, and groundwater because of accidental oil spill, leakage of gasoline and other petroleum fuels from underground storage tanks and pipelines, and improper oil-related waste disposal practices. In these cases, BTEX compounds can also be used as markers in identifying the presence and determining the composition of these weathered fuels originating from leaking underground fuel tanks or pipelines. BTEXs are hazardous carcinogenic and neurotoxic compounds and are classified as priority pollutants regulated by Environment Canada1 and the U.S. Environment Protection Agency (EPA),1 2 especially benzene, which has a very low tolerance standard in drinking water of 5 jtg/L.

The Use Of Chemical Composition And Additives To Classify Petrol And Diesel Using Gas Chromatography–Mass Spectrometry And Chemometric Analysis: A Uk Study

“…Gas Chromatography-Mass Spectrometry (GC-MS) is widely used as a primary method for characterization of fuels. Typical analyses performed usually involve the identification of certain compounds [2][3][4][5] , the use of ratios between chemicals [6,7,8] and identification and quantification of markers or additives [9][10][11][12]. Many previous studies successfully used GC-MS to determine the individual component composition and fuel additives.…”

Selective identification of mono‐ and polyaromatics in diesel fuel using gas‐phase chromatography coupled with high‐resolution negative ion mass spectrometry

“…Usually, chemical separations of aromatic components from saturated hydrocarbons followed by GC/MS are used to perform such analyses. All of these methods are well known in petroleum chemistry 1–18…”

Identification and Linkage of Tarballs from the Coasts of Vancouver Island and Northern California Using GC/MS and Isotopic Techniques

“…Among the other PAH, the loss of lower molecular weight PAH such as biphenyl, acenaphthylene, and acenaphthene, in comparison to ANS oil, is also obvious. The lack of volatile compounds, in conjunction with other compositional changes of alkylated PAH and other PAH, indicates that the unknown oils in all of the tarball samples have been highly weathered [29].…”