Porous graphitic carbon-based metabolomics and development of an alternative biomass-derived carbon stationary phase

In contrast to standard reversed-phase liquid chromatography (RP-LC) columns, porous graphitic carbon (PGC) stationary phase offers one solution to the separation of polar compounds. The unique retention mechanism of PGC, owing to its planar graphite-like sheet functionality, enables the separation of isomeric compounds. The use of RP-LC solvent systems allows direct coupling with electrospray mass spectrometry (ESI-MS) which enhances the types of analyses that can be performed with this stationary phase type still further. This thesis describes the use of on-line PGC-LC-ESI-MSn methods for the analysis of metabolites extracted from leaf blade samples from plant systems subjected to water deficit. The quantitative analysis of targeted carbohydrates in the resurrection plant Haberlea rhodopensis along with the untargeted analysis of water soluble metabolites in the model plant species Arabidopsis thaliana and Thellungiella salsuginea was performed. In addition, this thesis describes the optimisation of an alternative biomass-derived mesoporous carbon stationary phase, termed Starbon®, utilising the naturally porous material formed by expansion of the algal polysaccharide alginic acid in water. The effect of pyrolysis rate on the textural properties of Starbon® is investigated and shows that increased rates of pyrolysis reduce the inherent mesoporosity of the final carbon material. Several strategies are investigated in order to improve the particle size and morphology properties of Starbon®. These investigations have led to the development of a novel method of producing alginic acid-derived mesoporous carbon microspheres (AMCS). Commercial PGC, Starbon®, and AMCS-packed columns are compared in the separation of several carbohydrate standards. The column efficiency of the AMCS-packed column compares well to commercial PGC at low mobile phase flow rates. A study of the chemical microstructure of commercial PGC, Starbon®, and AMCS using microscopy and spectroscopy techniques is described. Starbon® and AMCS show abnormally high amounts of fullerene character compared to model non-graphitising carbons.