Mass spectrometric studies on lignin sequencing and fast pyrolysis, functional-group selective ion-molecule reactions and reactivity of bi- and triradicals

Due to the high sensitivity, selectivity and speed, mass spectrometry (MS) has proved to be an invaluable tool for mixture analysis and structural elucidation of mixture components. Tandem mass spectrometry (MS/MS) utilizing collision-activated dissociation (CAD) has become the technique of choice for structural elucidation of unknown analytes. The coupling of MS/MS with high performance liquid chromatography (HPLC) has allowed trace level analysis of components in very complex mixtures. Analysis of mixtures of lignin degradation products is a problematic area for mass spectrometry due to the highly complex lignin linkages present. Hence, study of lignin model compounds with varies linkage types is very helpful for the structural elucidation of unnknown lignins. Gas phase ion-molecule reaction can be useful in study of reaction kinetics and mechanism and even in probing the functional groups in unknown molecules. The functional group selective ion-molecule reaction has great potential for unknown drug metabolite identification The experiments described in this thesis were aimed at providing more detailed structural information of mixture components by using different mass spcetrometry based methods. Chapter 2 describes the instrumentation used for the research presented in this thesis. Chapter 3 discusses the synthetic procedures for all the model compounds used. Chapter 4 and 5 mainly esteablished two sequencing methods for lignin model compounds with β-O-4, β-O-4 and 5-5 linkages, which can be coupled with HPLC to achieve lignin mixture analysis in lignin biofuel samples. Chapter 6 described a fast pyrolysis method developed in collaboration with chemical engineers to detect primary fast pyrolysis products of these lignin model compounds. Chapter 7-10 focused on the methods development for identification of sulfone, sulfoxide, N-oxide and N-hydroxylamine using functional group selective ion-molecule reactions. This project is in collabration with AstraZeneca. Chapter 10 described the gas phase reactivity study of 2,7,9-tridehydroacridinium cation