Quantifying matrix complexity with the calculation of fractal dimensions from GC×GC chromatograms : a potential oil fingerprinting technique

Abstract

Gas chromatograms record molecular patterns according to the spatial separation afforded by the analytical method used and the type of mixture being analyzed. In this respect, the molecular complexity recorded in a gas chromatogram may be definable through the calculation of its fractal dimension. Fractals are a branch of mathematics that illuminate statistical elements in the spatial patterns of various complex forms. A fractal dimension is the measure of spatial complexity. For this thesis, the question is asked whether the molecular outputs recorded using gas chromatography results in a definable fractal dimensions? To do this, we quantified the matrix complexity of maltene fractions of various oils analyzed with comprehensive two-dimensional gas chromatography (GC×GC). A fundamental question addressed in this thesis is if fractal dimensions can be used as a new oil fingerprinting method? This study aims to find fractal dimensions in multiple samples of GC×GC chromatograms. These hypotheses are tested by analyzing a suit of oils and hydropyrolysates collected from various regions. These suites of oils have been previously determined to have different molecular complexities in their gas chromatograms, subsequently it is predicted that the fractal dimension of the more complex oils will be higher. The results of this study are fractal dimensions where calculated from the three different ocean bottom hydrothermal sites at Guaymas Basin, the Middle Valley and Escanaba Trough. The fractal dimension values did not correlate with expected trends of generation and maturation of sedimentary organic matter. Due to the lack of trends we focused the project on explaining what was wrong with the method, the program and the chromatograms. The results from the three different sites were inconclusive, but we expect that such results and analysis done can be helpful for anyone trying to relate fractal dimensions with oil and gas in the future.