Schematic diagram of the EI FT-ICR mass spectrometer, showing the ion source, ion optics, and vacuum system.
Schematic diagram of the volatile sample introduction system.
Mass spectrum of an -alkylbenzenes mixture obtained from ExxonMobil. The rf parameters for the accumulation and transfer octopoles are , and 190 and and , respectively. External ion accumulation period was , transfer interval was , and data-acquisition period was . The peaks are labeled as shown in Table I.
Relative abundances for components of a -alkylbenzene mixture, demonstrating the stability of the inlet system. The data are from eight compounds that span the entire mass range in Fig. 3.
Molecular ion signal-to-noise ratio vs external ion accumulation period for the same eight compounds as in Fig. 4.
FT-ICR mass spectrum of 1-bromo-2-chlorobenzene at electron energy, demonstrating the mass resolving power obtained at for a data-acquisition period. The mass scale-expanded segment (insert) demonstrates the base line separations of and , for which .
EI FT-ICR mass spectrum of unprocessed diesel fuel from a septum injection. Accumulation period was , transfer interval was , and data-acquisition period was . The inset mass windows show the baseline resolutions of and doublets at mass resolving power .
Mass scale-expanded segments of the unprocessed (top) and processed (bottom) diesel fuel mass spectra, identifying the sulfur-containing species. Note the complete removal of the benzothiophene series [with 14 additional methylene groups (a)] and methyldibenzothiophene (b), as well as the partial removal of the dibenzothiophenes with two additional methylene groups (c) by hydrotreatment.
Mass scale-expanded segments of the unprocessed (top) and processed (bottom) diesel fuel mass spectra, identifying various nitrogen- and oxygen-containing species. Note the persistence of species matching the structures of carbazole [with one (a) and two (b) additional methylene groups] and methyldibenzofuran (c).
Composition of the -alkylbenzenes mixture obtained from ExxonMobil.
Compound heteroatom classes and types (rings plus double bonds) in unprocessed and processed diesel fuels.
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