Abstract: Etherification of gasoline is the main way to produce gasoline with low olefin content and high octane number. With the upgrading of oil quality, the content of oxygen compounds in gasoline is strictly limited. At present, the main focus of ether compounds in gasoline are methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), methyl tert-amyl ether (TAME), diisopropyl ether (DIPE) and other C₅-C₆ ethers, but there are few reports on C₇ ethers. In this paper, a method for detecting C₇ ethers in gasoline was established by gas chromatography-oxygen selective flame ionization detector (GC-OFID). Compared with direct mass spectrometry and the NB/SH/T 0663-2014 standard method, hydrocarbons do not interfere with the determination of C₇ ethers by GC-OFID. The linear range (w) of the method was 1%-5%, the coefficient of determination r² was 0.999 9, and the detection limit (w) was 0.010% . Four structures of C₇ ethers were determined by GC-MS. The recoveries of C₇ ethers in automotive gasoline were 95.1%-103.5%, and the relative standard deviations (RSD, n=4) were 0.2%-0.6%. The method has good repeatability and high accuracy. The established method can be used for the determination of alcohols and ethers in gasoline samples from different process sources, which lays a foundation for the quality assurance of automotive gasoline.

Key words: C₇ ethers, gasoline, oxygen selective flame ionization detector, gas chromatography