Improvements in the GC/MS Analysis of Polycyclic Aromatics in Fossil Fuels: Sampling, Separation, and Assessment.
Abstract: The characterization of complex mixtures and accurate quantitation
of their components is a challenging endeavor, requiring the application of a powerful
analytical technique such as gas chromatography/mass spectrometry (GC/MS). The GC/MS
analysis of polycyclic aromatic compounds (PAC) in fossil fuels is particularly difficult
due to overlapping retention windows, common spectral ion... read mores, and sample matrices rife with
interfering compounds. PAC are persistent and harmful, and the fossil fuels that they
comprise are the predominant contaminant in thousands of hazardous waste sites worldwide.
Accordingly, facilitation of their analysis can have a broad-reaching impact on human and
environmental health. This work describes several lines of research to this end. An in situ
sample collection system that provides on-line continuous detection of environmental
pollutants was developed; technology that can unambiguously profile organics in the
subsurface from ground-level to bedrock. The effects of selected-ion data analysis methods
on diagnostic ratios used in environmental forensics were examined, and it was found that
methods employing fewer than three ions consistently overestimated alkylated homologue
concentrations and led to biased and inaccurate diagnostics. The retention behavior of
polycyclic aromatic sulfur heterocycles (PASH) on novel room temperature ionic liquid
stationary phases was investigated; these columns can provide improved separation of both
polars and nonpolars at higher temperatures than the columns typically utilized for the
analysis of fossil fuels. Comprehensive two-dimensional gas chromatography-quadrupole mass
spectrometry (GC×GC/qMS) spectra were deconvolved, allowing for the first quantitative
analysis of PAC in coal tar by this technique. And a simple and robust modeling technique
for estimation of physical properties from GC×GC retention indices was developed. This
method was embedded into a software program to produce a component map that provides, for
the first time, the ability to assess the weathering of complex mixtures such as crude oil
and coal tar by subsurface and sediment environments. In all, the work is relevant to all
aspects of the analysis of complex samples: sample collection and preparation,
chromatographic separation, data analysis, and utilization of these results in
Thesis (Ph.D.)--Tufts University, 2015.
Submitted to the Dept. of Chemistry.
Advisor: Albert Robbat.
Committee: Arthur Utz, Samuel Kounaves, and Richard Gaines.
Keywords: Chemistry, and Environmental science.read less