Patent ID: 9689859
Date: 2017-06-27
CPC Classifications: C10L,G01N

Claim:
1. A gas chromatographic method for detecting a first marker compound and a second marker compound in a petroleum hydrocarbon or a liquid biologically derived fuel; said method comprising providing two analysis channels, (i) and (ii); wherein channel (i) comprises a first capillary column which is an open tubular column coated with a polysiloxane stationary phase and a second capillary column which is an open tubular column coated with a polyethylene glycol; and channel (ii) comprises a third capillary column which is an open tubular column coated with a polymethylphenylsiloxane having at least 30 mole % phenyl substitution and a fourth capillary column which is a deactivated open tubular column; and said method comprising steps of: (a) determining retention times of the first marker compound in the first and second capillary columns and the second marker compound in the third and fourth capillary columns; (b) introducing a first sample of a petroleum hydrocarbon or a liquid biologically derived fuel into the first channel and allowing the first sample to flow through the first capillary column to produce a first effluent stream; (c) introducing only a portion of the first effluent stream having a retention time range which includes the retention time of the first marker compound into the second capillary column and allowing said portion of the first effluent stream to flow through the second capillary column to produce a second effluent stream; (d) allowing the second effluent stream to pass through a mass spectrometer; (e) introducing a second sample of a petroleum hydrocarbon or a liquid biologically derived fuel into the second channel and allowing the sample to flow through the third capillary column to produce a third effluent stream; (f) introducing only a portion of the third effluent stream having a retention time range which includes the retention time of the second marker compound into the fourth capillary column and allowing said portion of the third effluent stream to flow through the fourth capillary column to produce a fourth effluent stream; and (g) allowing the fourth effluent stream to pass through a mass spectrometer; wherein the first marker compound has formula Ar