Abstract
Discrimination between fuel oils A (No. 1 and No. 2 with less than 5000 and 20000 ppm of sulfur contents, respectively) and diesel fuel with less than 50 ppm of the sulfur content was studied using a gas chromatograph-mass spectrometer (GC-MS). Mass chromatograms (MC) of m/z 184, 198, and 212 for dibenzothiophene (DBT), methyldibenzothiophenes (C1-DBT), and dimethyldibenzothiophenes and ethyldibenzo thiophenes (C2-DBT), respectively, corresponded to the chromatograms of the compounds in the oils by gas chromatography-atomic emission detection. These compounds are main sulfur compounds in the oils. The MC analysis of DBT, C1-DBT, and C2-DBT could rapidly discriminate between the diesel fuel and the fuel oils A. In the case of analysis of contaminated oil samples, the oils were cleaned-up and fractionated into two fractions on a florisil column prior to the GC-MS analysis. The first and second fractions were eluted with hexane and hexane-chloroform (2 : 1), respectively. The second fraction contained sulfur compounds together with aromatic hydrocarbons. The MC analysis of the sulfur compounds in the second fraction also discriminated the three types of oils. This method has the advantage of requiring only a sub-microliter of sample amount and a scan mode of GC-MS measurement for the discrimination of the three types of oils.
