Mapping Environmental Partitioning Properties of Nonpolar Complex Mixtures by Use of GC × GC

Comprehensive two-dimensional gas
chromatography (GC × GC)
is effective for separating and quantifying nonpolar organic chemicals
in complex mixtures. Here we present a model to estimate 11 environmental
partitioning properties for nonpolar analytes based on GC × GC
chromatogram retention time information. The considered partitioning
properties span several phases including pure liquid, air, water,
octanol, hexadecane, particle natural organic matter, dissolved organic
matter, and organism lipids. The model training set and test sets
are based on a literature compilation of 648 individual experimental
partitioning property data. For a test set of 50 nonpolar environmental
contaminants, predicted partition coefficients exhibit root-mean-squared
errors ranging from 0.19 to 0.48 log unit, outperforming Abraham-type
solvation models for the same chemical set. The approach is applicable
to nonpolar organic chemicals containing C, H, F, Cl, Br, and I, having
boiling points ≤402 °C. The presented model is calibrated,
easy to apply, and requires the user only to identify a small set
of known analytes that adapt the model to the GC × GC instrument
program. The analyst can thus map partitioning property estimates
onto GC × GC chromatograms of complex mixtures. For example,
analyzed nonpolar chemicals can be screened for long-range transport
potential, aquatic bioaccumulation potential, arctic contamination
potential, and other characteristic partitioning behaviors.