CE-ESI-MS has become a powerful analytical tool capable of simultaneous identification and quantification of many classes of biologically relevant molecules. For studies in metabolomics, CE-ESI-MS offers a unique platform which will allow for the systematic elucidation of unknown metabolites in complex matrices without the need for complex sample preparation steps required with other techniques. In this thesis, a novel theoretical prediction model which will allow the estimation of detector response in ESIMS is outlined. This response model will allow researchers to quantitatively predict relative ionization effiency of compounds based on proposed two-dimensional structures without the need for a purified standard. Another feature of this model is that it can be applied to complex biological samples without the need for off-line sample pretreatment. Also in this thesis, a novel neonatal screening method will be presented which will aid clinical chemists in determining the presence of inborn metabolic disorders. This screening method which aims to compliment current protocols will allow health care professionals to further assess dried blood spot samples by providing simultaneous separation, identification, and quantification of relevant metabolites. This method also offers an alternatives to other protocols in place which are necessary to measure acid labile compounds which cannot be assessed by standard screening techniques. / Thesis / Master of Science (MSc)

Lignin, the second most abundant naturally occurring polymer found in plant cell wall has the potential of becoming an alternative source for the production of chemical synthons for the pharmaceuticals and other chemical industries. While much gain has been made towards the development of degradation methods to break down lignin, effective analytical methods are still required to rapidly and accurately identify the products of lignin breakdown experiments. The goal of this work was to develop mass spectrometric methods for the characterization of lignin oligomers based on the study of model lignin compounds. Unlike peptides and oligosaccharides, lignin model compounds that could serve as analytical standards for methods developments are not commercially available, and hence, the first project of this dissertation focused on the synthesis of lignin model compounds containing the β-O-4 bond. The priority was to synthesize compounds containing all important functionalities that reflect the structure of native lignin. By employing the known Aldol reaction, lignin oligomers containing the β-O-4 were synthesized. The synthesized β-O-4 lignin oligomers contained the characteristic functional groups of native β-O-4 lignin, that is, the phenolic functionality, the aryl glycerol β-O-4 aryl ether bond and the unsaturated side chain. The second project was aimed at developing alternative ionization methods for the characterization of lignin in the negative ion mode mass spectrometry. A chloride adduct ionization method was developed and used for characterizing and sequencing lignin oligomers. This method proved to be very useful in stabilizing the adduct ion in the full scan spectrum mode and also providing useful structural information upon tandem mass spectrometry. In the third project, a cationization technique was developed to unambiguously assign the sequence in which β-O-4 lignin oligomers are connected. A simple and easy to use sequencing chart was designed and could serve as a guide for predicting the sequence of larger lignin oligomers. This method offers an alternative approach for the characterization of lignin oligomers in the positive ion mode mass spectrometry. The fourth project focused on the ionization response of a new class of β-O-4 lignin compounds. β-O-4 compounds having the same skeletal backbone but different non-polar groups at the a-position were synthesized, and their ESI response studied. Results from this study show that a slight change in the structure of a β-O-4 lignin model compound can change the cationization response to several order of magnitude. Most importantly, this work for the first time has shown a direct correlation between lignin ionization response and lignin structure. The fifth project was aimed at studying the chromatographic behavior of the diastereomer pair in β-O-4 lignin model compounds. Using three commercially available HPLC columns, the chromatographic behavior and factors that affect the separation of the diastereomer pair of the β-O-4 lignin diastereomer on an HPLC column were studied. By performing tandem mass spectrometry on each of the diastereomers, a fragmentation mechanism was developed that could be used to unambiguous assign the configuration (erythro or threo) for the pair of diastereomer in a β-O-4 model. The results presented in this dissertation adds significant knowledge to the lignin mass spectrometry literature, and it offers new ionization techniques for the characterization of lignin oligomers, most importantly, an alternative approach for lignin analysis using adduct ionization mass spectrometry. The developed methods could easily be extended for the characterization of larger lignin oligomers.