Deducing molecular compositions of petroleum products using GC-field ionization high resolution time of flight mass spectrometry

GC-field ionization high resolution time of flight mass spectrometry provides three-dimensional separations of complex mixtures. The first dimension is the gas chromatography retention time. This dimension can be either a boiling point scale or relative polarity scale depending on the type of GC column used in the separation. The second dimension is the molecular weight. This dimension is achieved by soft ionization of molecules and measurement of m/z values of largely singly charged species. The third dimension arises from chemical mass defects associated with heteroatom content and degree of unsaturation. This dimension is established by high resolution and accurate mass capabilities. Highly detailed compositional information can be obtained when the three-dimensional separation is applied to petroleum products. Quantitative applications of the approach require careful response factor calibrations.