| The conversion of cellulosic material to ethanol begins with a dilute acid pretreatment to remove hemicellulose and alter the lignin distribution. Despite successful conversions, spatial changes of chemical composition throughout pretreatment are not well characterized. Developing nondestructive analytical methods to visualize changes that occur in biomass throughout the pretreatment processes could help increase efficient of biomass conversion into biofuels.;MALDI-mass spectrometric imaging (MS imaging) in a powerful analytical technique that displays a distribution of target molecules in intact tissue. MALDI-TOF (time-of-flight)-MS is commonly used to characterize polysaccharides, but tandem MS capabilities of a TOF are limited. The linear ion trap (LIT) mass analyzer offers tandem MS capabilities, which can provide structural information and monosaccharide composition of polysaccharides.;A MALDI-LIT tandem MS method was developed for to characterize three plant-related standards, microcrystalline cellulose (MCC), Birch xylan and Spruce lignin. The standard analysis determined the ions that are formed from MALDI and provide characteristic fragmentation pathways of these standard compound classes. MALDI-MS imaging of intact Populus tissue sections illustrated a nearly even ion signal across the whole tissue. In contrast, tandem MS imaging was able to differentiate between isobaric ions to provide sensitive and selective than single-stage MS imaging of these compound classes. The tandem MS images showed localization of cellulose in the secondary xylem and phloem fiber cells, which are both known to have thickened secondary cell walls.;High correlation between MALDI tandem MS imaging, fluorescence imaging and ToF-SIMS imaging was observed. In addition, ToF-SIMS imaging provided a high spatial resolution, chemically selective images to characterize the material further. Principal component analysis (PCA) of MALDI-MS analysis of standards and ToF-SIMS imaging determined ions characteristic of lignified and non-lignified tissue.;In conclusion, this dissertation reports a comprehensive analysis of lignocellulosic material (LCM) using three different techniques, MALDI-LIT tandem MS imaging, fluorescence microscopy and ToF-SIMS imaging. Combining the information obtained from these techniques provided a more complete analysis of the tissue sections. Furthermore, the tools for analysis of LCM throughout a pretreatment analysis have been developed. |
