Complete Group-Type Quantification of Petroleum Middle Distillates Based on Comprehensive Two-Dimensional Gas Chromatography Time-of-Flight Mass Spectrometry (GCxGC-TOFMS) and Visual Basic Scripting

The subject of the presented work was the development of a two-dimensional GCxGC time-of-flight mass spectrometric method (GCxGC-TOFMS) for the complete group-type quantification of petroleum middle distillates. The development of this method was possible due to the inherent features of GCxGC-TOFMS, namely the structured arrangement of compound groups and the mass fragmentation pattern, which provide the possibility of using Visual Basic Scripts as an analytical tool and thereby the classification of several thousand different compounds. The analysis method was focused on common petroleum based fuels from light to heavier middle distillation fractions. For the implementation of an absolute quantification method, a set of standard substances representing the main substance classes and carbon numbers within middle distillates and well-separated and recognizable internal standards were thoroughly chosen in order to obtain individual response factors and group specific response curves. The results of the qualitative and quantitative analysis were compared to well-established standard methods used in the petrochemical industry. The quantification of aromatic hydrocarbons was compared to EN 12916, a high performance liquid chromatography (HPLC) method that provides a rough separation between mono-, di-, and higher aromatics. Further, the quantification of the fatty acid methyl ester (FAME) content in diesel fuel was compared to EN 14078 and the distribution of single FAMEs was compared to EN 14103. It could be stated that an absolute quantification as the here presented method has not been reported before and the results were in good agreement with the reference methods. Furthermore, the here presented GCxGC-TOFMS quantification method is able to itemize according substance classes and carbon number. The detection limit of the method allows accurate and sensitive quantification for different limiting values of middle distillates with a single method.