Comparison of GC-VUV, GC-FID, and comprehensive two-dimensional GC-MS for the characterization of weathered and unweathered diesel fuels

Characterization of diesel fuels and degraded diesel fuels in the environment is a common issue nowadays. Providing definitive information for litigation regarding determination and distinguishing the origins or sources of fuel spill contamination has been a significant need among the environmental forensics community. Diesel fuels contain more complex chemicals and isomers compared to gasoline. Here, we compare the use of gas chromatography - vacuum ultraviolet spectroscopy (GC-VUV), gas chromatography - flame ionization detection (GC-FID), and comprehensive two-dimensional gas chromatography - mass spectrometry (GC × GC-MS) for diesel fuel and weathered diesel fuel analysis in fingerprinting biomarkers. GC-VUV is a relatively new technique that can rapidly acquire full absorption spectra from 120 to 240 nm. Class information about individual components is readily obtained based on reference to a library of matched spectra. Direct comparison of GC-VUV, GC-FID, and GC × GC-MS was undertaken to identify different classes of compounds and biomarkers. Using GC-VUV, numerous peaks representing minor and major components were classified into different classes by applying spectral filters and, in some cases, spectral deconvolution. Isoprenoid biomarkers, such as pristane and phytane, and their ratios with n-alkanes, C17 and C18, respectively, were determined The biomarker ratio results from GC-VUV matched well with both GC-FID and GC × GC-MS. About 5%-20% difference in measured biomarker ratios were obtained for a series of commercial weathered diesel standard samples, which is good enough to allow the discrimination of different weathered diesel samples, according to prior literature.