Complete Compositional Monitoring of the Weathering of Transportation Fuels Based on Elemental Compositions from Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

We have determined elemental compositions for hundreds of components of diesel fuel, jet fuel (JP-8), and gasoline and characterized each of their chemical compositions before and after artificial “weathering” (i.e., evaporation to a specified fraction of the original weight). An all-glass heated inlet system (AGHIS) coupled to a home-built 6.0 T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer provides ultrahigh mass resolving power (m/Δ m 50% > 100 000, in which Δ m 50% is the full peak width at half-maximum peak height) and sufficiently high mass accuracy (≤0.8 ppm) for unique identification of all chemical components. A 1 μL septum injection of each weathered/unweathered transportation fuel into the AGHIS yields a mass spectrum containing 100−500 peaks, 50 ≤ m / z ≤ 300, with as many as five peaks (of different elemental composition) at a given nominal mass. Elemental composition assignment of every peak in the mass spectrum of each fuel and its weathered analogues provides a unique chemical “fingerprint” that serves to identify positively the contaminant and quantitate the extent of weathering. Weathered jet and diesel fuels (and gasoline to a lesser extent) exhibit a significant shift in the relative abundance to higher-mass ( m / z ≥ 200) species, in accord with prior gas chromatographic (GC) evidence for a shift toward increased retention time with increased degree of weathering.