Mono-aromatic complexity in urban air and gasoline assessed using comprehensive GC and fast GC-TOF/MS.

Two state-of-the-art analytical techniques have been used to assess mono-aromatic complexity in gasoline, gasoline vapors and polluted urban air. A comparison of comprehensive gas chromatography (GCxGC) and fast gas chromatography - time-of-flight mass spectrometry (GC-TOF-MS) has been made, with emphasis on the ability of each technique to speciate at high isomeric complexity. The high spectral acquisition rates from TOF-MS gave improved peak deconvolution of overlapping analytes when compared to standard quadrupole configurations, with 89 mono-aromatic isomers isolated in gasoline in a 200 s GC separation. Highest resolution was obtained using GCxGC, isolating 140 mono-aromatics, using combined column retention behavior for analyte identification. Analysis of urban air using GCxGC indicated the presence of 136 mono-aromatic species with up to 7 carbon substituents on the ring. Comparison of 3D GCxGC chromatograms for air and gasoline vapors demonstrated visually the impact of evaporative emission sources in urban environments. The potential contribution of larger mono-aromatic compounds as precursors to both photochemical ozone and secondary organic aerosol is discussed along with the implications on modeling OH chemistry in polluted air.