Determination of Oxygenates in Gasoline Range Hydrocarbons by Capillary Column Gas Chromatography: A User's Experience with an Oxygen-Specific Detector (OFID)

The determination of oxygenates in gasoline boiling range hydrocarbons by flame ionization oxygen-specific detection (OFID) has recently been described in the literature. This paper describes the installation and optimization of a stand-alone commercially available OFID on a Varian 6000 gas chromatograph. The FID base is modified for the insertion of the methanizer reactor. The most difficult problem in the optimization of the OFID is the presence of oxygen from small air leaks in the hardware, which renders the OFID unusable. A simple procedure is developed for detecting and eliminating leaks. A method is developed for the determination of 1–15 vol % methanol, ethanol, t-butyl alcohol, and methyl t-butyl ether (MTBE) in gasoline boiling range hydrocarbons on a thick-film nonpolar column. To attain acceptable repeatability (less than 2% relative) and theoretical response factors it is necessary to optimize the injection port splitter.