Stationary phase selection and comprehensive two-dimensional gas chromatographic analysis of trace biodiesel in petroleum-based fuel

The GC × GC solvation parameter model has been used to identify effective stationary phases for the separation of fatty acid methyl esters (FAMEs) from petroleum hydrocarbons. This simple mathematical model was used to screen the 1225 different combinations of 50 stationary phases. The most promising pairs combined a poly(methyltrifluoropropylsiloxane) stationary phase with a poly(dimethyldiphenylsiloxane) stationary phase. The theoretical results were experimentally tested by equipping a GC × GC instrument with a DB-210 primary stationary phase and an HP-50+ secondary stationary phase. This instrument was used to analyze trace levels of FAMEs in kerosene. The FAMEs were fully separated from the petroleum hydrocarbons on the secondary dimension of the 2-D chromatogram. The resulting GC × GC method was shown to be capable of accurately quantifying FAME levels as low as 2 ppm (w/w). These results demonstrate the utility of the solvation parameter model for identifying optimal stationary phases for high resolution GC × GC separations. Furthermore, this work presents an effective method for determining the level of biodiesel contamination in aviation fuel and other petroleum-based fuels.