Patent ID: 7153694

Claim:
A method of operating a calibrated gas chromatograph/mass spectrometer system for analysis of the chemical and physical properties of a complex mixture of hydrocarbons with a boiling range between about 10° C. and about 705° C., said complex mixture of hydrocarbons comprising gasoline and olefins, which method includes hydrocarbon speciation in the boiling range between about 23° C. and about 260° C., said method comprising: introducing a sample of the complex mixture of hydrocarbons into the gas chromatograph to (partially) separate the mixture into its constituent components; ionizing the resulting components via Townsend discharge nitric oxide chemical ionization; introducing the resulting ionized components into the mass spectrometer to produce corresponding mass spectra; and, measuring, from the resulting mass spectra, the concentrations of individual hydrocarbon species and structural types comprising n-paraffins, iso-paraffins, cyclics, branched mono olefins, linear mono olefins, diolefins, cyclic olefins, cyclic diolefins, mono aromatics, indane/indenes, diaromatics, dicyclics, and benzothiophenes/dibenzothiophenes with in certain boiling ranges.