Modeling the GCxGC Elution Patterns of a Hydrocarbon Structure Library To Innovate Environmental Risk Assessments of Petroleum Substances

Comprehensive two-dimensional gas chromatography (GCxGC)
offers
unrivaled separation of petroleum substances, which can contain thousands
of constituents or more. However, interpreting substance compositions
from GCxGC data is costly and requires expertise. To facilitate environmental
risk assessments, industries provide aggregated compositional information
known as “hydrocarbon blocks” (HCBs), but these proprietary
methods do not transparently associate the HCBs with GCxGC chromatogram
data. These obstacles frustrate efforts to study the environmental
risks of petroleum substances and associated environmental samples.
To address this problem, we developed a GCxGC elution model for user-defined
petroleum substance compositions. We calibrated the elution model
to experimental GCxGC retention times of 56 known hydrocarbons by
fitting three tunable model parameters to two candidate instrument
methods. With the calibrated model, we simulated retention times for
a library of 15,447–15,455 hydrocarbon structures (plus 40–48
predicted as chromatographically unretained) spanning 11 classes of
petroleum substance constituents in the C10–C30 range. The resulting simulation data reveal that GCxGC retention
times are quantitatively associated with hydrocarbon class and carbon
number information throughout the GCxGC chromatogram. These innovations
enable the development of transparent and efficient technical methods
to investigate the chemical compositions and environmental properties
of petroleum substances, including in environmental and lab-weathered
samples.