This study investigated the cracking chemistry as model lipids were reacted over a benchmark catalyst, H-ZSM-5, and two industrially used catalysts, faujasite and silica-alumina. Initial work began with a homogeneous system in which oleic acid, an unsaturated free fatty acid, and triflic acid, a Bronsted superacid, were reacted at low temperatures. Results indicated that protonation began at the double bond with cracking occurring in the direction away from the carboxylic end and producing a multiplicity of branched saturated fatty acids. Heterogeneous cracking on H-ZSM-5 at 400°C indicated that acylglycerides initially crack due to protonation occurring on the outside surface of the catalyst. Secondary cracking formed olefins (C2 – C4) which then oligomerize to form aromatic hydrocarbons that were within the range of components for gasoline. Catalysis using faujasite and silica-alumina indicated that acylglycerides require milder cracking conditions than typical crude petroleum, indicating that lower temperatures and lower catalyst to feed ratios will be required to achieve the same reactant conversions as seen in petroleum refineries.

No description available.

No description available.

No description available.

The extraction and recovery of trace organic material from semi-solid and solid matrices is often the slowest and most error-prone step of an analytical method. The conventional liquid extraction techniques for solids and semi-solids materials (Soxhlet) have two main disadvantages. The first, large volumes of organic solvent are required, which can lead to sample contamination and "losses" due to volatilization during concentration steps. The second, to achieve an exhaustive extraction can require several hours to days. With the development of sophisticated instrumentation with detection limits in the picogram and femtogram levels, pressure is finally felt within the analytical community to develop and validate sample preparation procedures which can be used to rapidly isolate trace level organics from complex matrices.Because of its applicability to solid, semi-solid, and liquid matrices microwave-assisted (MAE) extraction has emerged as a powerful sample preparation technique. The objective of this research was to evaluate directly focused microwave energy for the isolation of systemic fungicide residues from woody plant tissues.The hallmark of microwave extraction (MAE) is accelerated dissolution kinetics as a consequence of the rapid heating processes that occur when a microwave field is applied to a sample. The current popularity of MAE resides mainly on its applicability to a wide range of sample types because the selectivity can be easily manipulated by altering solvent polarities.Propiconazole is a systemic fungicide, used to combat the fungal pathogen Ophiostoma ulmi, the casual agent of Dutch elm disease (DED). It was successfully extracted from treated Ulmus americana (elm tree) using MAE with a percent recovery of 395% in 15 minutes. Until now, techniques for rapid and efficient extraction of polar material from wood were non-existent. This work produces results much quicker than Supercritical Fluid Extraction (SFE). The influence of pH, microwave power, and time on extraction efficiency was also investigated. The extraction methodology was optimized and statistically validated.This MAE method combined with GC-MS was used to study the diffusion patterns and degradation of propiconazole in tree bark over extended time periods. Because of the complex nature of woody plant systems, it was realized that a more theoretical means must be used to determine the degradation rate of propiconazole in water systems. As a result, propiconazole was reacted with water under controlled temperature and pH conditions; to measure the degradation rate of propiconazole.The internal pH of elm sap is about 6.0; the slightly acidic environment and natural enzymes within the xylem vessels are known to catalyze the degradation of propiconazole (1). Novartis Inc. has marketed propiconazole as having fungicidal effects in injected elms for nearly two years. Our degradation studies have indicated much shorter lifetimes. To confirm our fate studies, the activation energy for the degradation reaction of propiconazole was calculated. This information provided valuable insight into revising dosage and treatment frequency for maximum protection of the elm against Dutch elm disease. Anti-fungal activity among metabolites was also explored. This is the first reported use of MAE to monitor the degradation of systemic pesticides in woody plant material. / Ph. D.

Hop (Humulus lupulus L.) is an indispensable raw material in beer brewing because it can provide unique aroma and bitterness to beer products. With growing consumer interests in locally-sourced ingredients and increasing number of microbreweries, hop production is emerging in many non-traditional U.S. growing regions like Virginia (VA). However, the lack of understanding on aroma chemistry of regional hops limited their prosperity. Moreover, suitable postharvest drying and packaging practices for VA hop producers are not available. This dissertation aims to address above issues by investigating the aroma chemistry of VA hops by varieties (Cascade, Chinook), growing locations (Meadowview/Petersburg/Blacksburg, VA), smaller-scale drying practices (oven drying, dehydrator drying, freeze drying) and packaging materials (PA/PE, OPP/Foil/PE, EVOH). Our efforts also extended to the novel application of hop-derived ingredients in non-beer drinks to promote value-added products. Solid phase microextraction and solvent-assisted flavor evaporation were applied for aroma extraction. Gas chromatography-mass spectrometry-olfactometry was used with stable isotope dilution analysis and standard addition method for accurate quantitation of aroma-active compounds. A total of 33 and 36 aroma-active compounds were identified in all fresh and dried hops, respectively. Geraniol, β-myrcene, linalool, methyl octanoate and trans-α-bergamotene were found to be the predominant compounds. Aroma profiles varied significantly with growing locations for both varieties. Individual aroma contents and total essential oil were the highest in dehydrator-dried hops, indicating the advantage of dehydrator-drying being a suitable practice to retain aroma power in hops for most smaller-scale producers in VA. Most volatile compounds in different packaged dried hops showed decreased concentrations over 8-month storage, but the variation was not statistically significant. Hop essential oil (HEO) microcapsules, manufactured by spray drying using modified starch CAPSUL® as the wall material, showed high flavor retention and controlled aroma release. The addition of HEO microcapsules significantly improved the aroma recovery and stability in hop tea. Our findings enhance the understanding of the aroma chemistry in regional hops as affected by multiple pre- and postharvest factors. The novel non-beer application of HEO was also successfully demonstrated. / Doctor of Philosophy / Hop (Humulus lupulus L.) is an essential raw material in beer brewing because it can provide beer products with unique flavor. With the growing "buy local" trend among consumers in recent years, hop production is moving to many non-traditional growing regions in the U.S. including Virginia. This resulted in an increasing number of local craft breweries operating on a smaller scale across the state. However, the aroma characteristics of Virginia-grown hops are unclear. Specific suggestions related to hop postharvest processing and storage are also unavailable for regional smaller-scale hop producers. Therefore, this study aims to study the aroma characteristics of Virginia-grown hops by varieties, growing locations, smaller-scale drying practices and packaging strategies. The novel non-alcoholic application of hop essential oil (HEO, mixture of many hop aroma compounds) was also demonstrated in hop tea. The results showed that both fresh and dried Virginia hops had a complicated profile of aroma compounds that primarily exhibited typical citrus, woody and fruity attributes. Both Cascade and Chinook varieties harvested from Meadowview showed significantly higher aroma contents than hops harvested from the other two locations in Virginia. Most aroma compounds in hops were better preserved by dehydrator drying than freeze an oven drying. No significant change was observed in aroma compositions from hops packaged in three different materials after storage. Finally, HEO particles with enhanced stability were prepared by engineering approaches, which were finally added to hop tea bags for the evaluation of aroma-intensifying effects and storage stability. The results indicated an overall desirable characteristic for the obtained HEO particles. The addition of HEO particles could significantly enhance the aroma stability of hop tea products during storage. Overall, the findings from this study enable a better understanding of flavor chemistry of regional hops from various origins and demonstrated a successful application of HEO particles as a flavoring agent in non-beer products.

Persistent interest in edamame, vegetable soybean (Glycine max (L.) Merr.), by U.S. consumers has continued to fuel the development of a domestic edamame supply chain. Studies have shown edamame to be a nutritious specialty crop with potential to provide economic benefit to local growers. Domestically bred and grown edamame has shown to be preferred by growers and consumers with competitive agronomic traits. While domestic varieties of edamame will encourage growers to produce a product catered towards the domestic market, additional considerations of final product quality are necessary to positively influence the market success. Domestically grown and store-bought edamame samples were utilized to research quality attributes including flavor, taste, and texture of edamame representative of domestic market and supply chain. Solid phase microextraction was utilized for aroma extraction prior to gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) analyses to obtain (1) impactful volatile compounds present, (2) changes in these compounds by stink bug feeding injury, and (3) volatile contributions to sensory characteristics. Sensory methods were utilized to (1) evaluate differences in perception of edamame with and without stink bug feeding injury, and (2) understand important sensory characteristics for domestic edamame. Volatile analysis recognized 16 volatile compounds when investigating edamame genotypes with 14 compounds having significant differences in contents by genotype. Only 10 compounds were consistently detected through GC-O by panelists, so called aroma-active compounds, and only one compound (E)-2-octenal was significantly different in odor intensities across genotypes. Stink bug injured samples showed dramatic differences in volatile profile compared with the not injured counterpart, from mass chromatogram; however, no noticeable differences were perceived by GC-O or sensory difference testing. An instrumental texture analysis method was proven to be sensitive enough to detect the textural differences of edamame beans after processing. The multi-dimensional sensory characteristics including taste, aroma, and texture, were established showing significant differences by edamame variety and growing location. Domestically bred edamame was found to be sweeter, as is preferred by domestic consumers, confirming encouraging breeding outcome. Despite significant differences in edamame volatile profiles by genotype and stink bug feeding injury, sensory discrimination of these differences seems to be less noticeable than changes from taste and texture. Utilizing our findings toward future research and product development will support the domestic edamame supply chain by providing a foundational understanding of quality attributes and their impacts. / Doctor of Philosophy / Edamame, or vegetable soybean (Glycine max (L.) Merr.), has been gaining popularity in the U.S. as plant based and alternative proteins continue to see increased attention. Research has shown edamame to be a nutritious specialty crop with potential to provide economic benefit to local growers. Edamame developed and grown in the U.S. has been shown to be preferred by growers and consumers. Understanding the quality of these products is important for a positive and lasting presence in the market. In this work, locally grown edamame as well as storebought edamame were investigated for flavor and texture. Chemistry methods to research volatile compounds were used to determine impactful flavor compounds, changes in these compounds caused by stink bug injury, and specific aroma of these compounds in edamame. Sensory methods were used to determine differences in edamame injured by stink bugs and to determine taste, flavor, and texture terms related to local edamame. This work identified 16 volatile compounds consistently in edamame samples with 14 being found to vary in amount by edamame genotype. Only 10 volatile compounds were detected through human sniffing results with only one being found to vary in amount of aroma detected by edamame genotype. Edamame showing visual signs of stink bug feeding injury showed different amounts of chemical compounds compared to the uninjured edamame, but aroma detected by human sniffing and sensory evaluation did not show differences. A method using a texture instrument was proven to be sensitive enough to detect even minor differences of edamame beans by texture. Sensory qualities including taste, aroma, and texture, were found to have differences in edamame based on edamame variety and growing location of the edamame. Locally bred and grown edamame was found to be sweeter than comparable edamame, as is preferred by consumer in the U.S. Despite differences in volatile compounds in edamame as identified in volatile analysis by differences in stink bug feeding injury, edamame genotype, and growing location, detection of these differences through aroma and taste by human panelists is not seen in this work. Providing these understanding of sensory qualities and their impact on the edamame will help support the local edamame supply in decision making and product development.

No / Irregular residues of a yellow deposit that was assumed to be seal fat used for waterproofing were observed in the creases of the outer surface of a pair of Inuit boots from Arctic Canada. A sample of this deposit detached from one of these areas on these boots was examined initially by FT-Raman microscopy, from which interesting and rather surprising results demanded further analysis using FT-IR and GC-MS. The non-destructive Raman spectroscopic analysis yielded spectra which indicated the presence of a tree resin from the Pinaceae sp. The Raman spectra were also characteristic of a well-preserved keratotic protein and indicative of adherent skin. Subsequent FT-IR spectroscopic analysis supported the attribution of a Pinaceae resin to the yellow deposit. GC-MS analysis of the same deposits identified the presence of pimaric, sandaracopimaric, dehydroabietic and abietic acids, all indicative of an aged Pinaceae resin. These results confirmed that the Inuit people had access to tree resins which they probably used as a waterproofing agent.

Le cycle de Krebs occupe une place centrale dans le métabolisme cellulaire et est le point de jonction de nombreuses voies essentielles. Depuis le début des années 2000, un lien a été démontré entre l’apparition de certains cancers et des mutations affectant des gènes codant pour des enzymes du cycle de Krebs, i.e., la succinate déshydrogénase, la fumarase ou les iso-enzymes 1 et 2 de l'isocitrate déshydrogénase (IDH). Les mutations des gènes IDH sont présentes dans 15 à 20 % des leucémies myéloïdes aigues (LAM) et jusqu'à 80 % dans certains gliomes. Ces mutations affectent le site actif des enzymes et elles induisent une néo-fonction enzymatique qui se traduit par la production et l'accumulation d'un oncométabolite : le stéréoisomère D du 2-hydroxyglutarate (D-2-HG) responsable de dérégulations énergétiques et épigénétiques au sein de la cellule. Afin de mieux comprendre les mécanismes mis en jeu entre ces anomalies et la pathologie humaine, mon travail de thèse a impliqué le développement de différentes méthodes analytiques : - tout d'abord une méthode robuste de séparation et de quantification des stéréoisomères D et L par dérivation chirale du 2-HG, ceci en GC tandem MS, - également par GC tandem MS, des méthodes métabolomiques ciblées à haute spécificité pour l'analyse de plus de 120 composés d'intérêt clinique, - des méthodes analytiques à haute résolution et non-ciblées (masse exacte; n=360 composés) adaptées à l'étude de cellules, - et des méthodes d'étude de flux métaboliques sur culture cellulaire basées sur l'analyse des dérivés de traceurs marqués aux isotopes stables. Le développement de ces méthodes m'a permis d'obtenir les résultats suivants. J'ai démontré l'importance du D-2-HG comme marqueur de la présence de mutations IDH1/2 dans une large cohorte de patients leucémiques, à la fois pour le diagnostic et pour le suivi des patients sous traitement. Notre étude pilote a conduit à utiliser ce paramètre en pratique hospitalière courante dans le laboratoire de chimie analytique de l'institut Gustave Roussy (IGR; Villejuif). L'étude de profils métaboliques associés aux mutations affectant les enzymes IDH2 et succinate déshydrogénase nous a permis d'identifier des mécanismes compensatoires du dysfonctionnement du cycle de Krebs, par exemple la sur-activation de la pyruvate carboxylase. Nous avons par ailleurs montré que ces mécanismes ne sont que partiellement efficaces; ils pourraient ainsi servir de cibles thérapeutiques. Une mutation du gène IDH2 (R140Q) est retrouvée chez des patients atteint de LAM et chez des patients possédant une acidurie D-2-hydroxyglutarique, maladie héréditaire du métabolisme extrêmement rare. Un inhibiteur spécifique de l'enzyme IDH2 possédant la mutation R140Q est actuellement testé comme traitement dans un essai clinique à l'IGR pour les patients leucémiques. Nous avons étudié les effets de ce composé sur des fibroblastes de notre patient atteint d'acidurie D-2-hydroxyglutarique. Nous avons confirmé ses effets sur l'enzyme IDH et observé des effets secondaires sur le métabolisme des lipides et du cycle de Krebs, à la fois dans les fibroblastes témoin et du patient. Cet inhibiteur étant connu pour avoir des effets sur la différenciation cellulaire, nos résultats pourraient permettre d'expliquer les mécanismes impliqués. Ce travail a apporté de nouveaux outils pour l'exploration des maladies métaboliques traditionnelles ainsi que de certains types de cancers, et il met en avant de nouvelles illustrations de la puissance de l'approche métabolique pour identifier des points d'intervention et de surveillance thérapeutique personnalisée des patients ("théranostique"). / The Krebs cycle has a central role in cellular metabolism and is at the junction of many essential pathways. Since 2000, a link has been shown between the development of particular cancers and mutations affecting genes coding for several Krebs cycle enzymes, i.e., succinate dehydrogenase, fumarase or iso-enzymes 1 and 2 of the isocitrate dehydrogenase (IDH). The IDH mutations are found in 15 to 20 % of acute myeloid leukemias and up to 80% of specific gliomas. These mutations affect the enzyme active site and are responsible for an neomorphic activity that is the production and accumulation of a putative oncometabolite : the D stereoisomer of the 2-hydroxyglutarate (D-2-HG) which is linked to energetic and epigenetic deregulations in the cell. To better understand the mechanisms between these abnormalities and human pathology, my PhD work involved the development of different analytical tools : - First of all, a robust method of separation and quantification of the stereoisomers D and L by chiral derivatization of the 2-HG, in tandem mass spectrometry, - GC tandem MS was also used to develop targeted metabolomic methods with high specificity for the analysis of more than 120 compounds of clinical interest, - An analytical non-targeted method using high mass resolution (exact mass; n=360 compounds) adapted to the study of fibroblast cells, - and finally, methods for the study of metabolic flux in culture cell based on derivatives of stable labeled tracers. The development of these methods led to the following results. I highlight the importance of the D-2-HG as a biomarker of the presence of IDH1/2 mutations in a large cohort of leukemic patients, for the diagnostic and the follow-up of patients under treatment. Our pilot study was the starting point for routine usage of this test in the clinical setting at the Institut Gustave Roussy (IGR; Villejuif). The study of metabolic profiles related to the mutations affecting IDH enzymes and succinate dehydrogenase allowed us to identify compensatory mechanisms of the dysfunction of the Krebs cycle, notably, the overactivation of pyruvate carboxylase. Moreover, we have shown that because these mechanisms are only partially efficient; they have potential to provide therapeutic targets. An IDH2(R140Q) mutation is shared between patients with AML and patients with D-2-hydroxyglutaric aciduria, a very rare hereditary disease of the metabolism. A specific inhibitor of the IDH2 enzyme mutant for R140Q is currently used in a clinical trial at the IGR institute. We studied the effects of this compound in fibroblasts of our aciduria patient. We confirmed the expected effect in the IDH enzyme and also observed moderate off-target effects concerning the lipid and the Krebs cycle metabolism, both in control and patient fibroblasts. Because this inhibitor is known to have effects in the cellular differentiation, our results could explain the underlying mechanisms. This work provides new tools for the exploration of traditional inherited metabolic diseases, as well as particular cancers, and illustrates the power of the metabolic approach to identify therapeutic targets and for the personalized monitoring of patients ("theranostics").

Le cycle de Krebs occupe une place centrale dans le métabolisme cellulaire et est le point de jonction de nombreuses voies essentielles. Depuis le début des années 2000, un lien a été démontré entre l’apparition de certains cancers et des mutations affectant des gènes codant pour des enzymes du cycle de Krebs, i.e., la succinate déshydrogénase, la fumarase ou les iso-enzymes 1 et 2 de l'isocitrate déshydrogénase (IDH). Les mutations des gènes IDH sont présentes dans 15 à 20 % des leucémies myéloïdes aigues (LAM) et jusqu'à 80 % dans certains gliomes. Ces mutations affectent le site actif des enzymes et elles induisent une néo-fonction enzymatique qui se traduit par la production et l'accumulation d'un oncométabolite : le stéréoisomère D du 2-hydroxyglutarate (D-2-HG) responsable de dérégulations énergétiques et épigénétiques au sein de la cellule. Afin de mieux comprendre les mécanismes mis en jeu entre ces anomalies et la pathologie humaine, mon travail de thèse a impliqué le développement de différentes méthodes analytiques : - tout d'abord une méthode robuste de séparation et de quantification des stéréoisomères D et L par dérivation chirale du 2-HG, ceci en GC tandem MS, - également par GC tandem MS, des méthodes métabolomiques ciblées à haute spécificité pour l'analyse de plus de 120 composés d'intérêt clinique, - des méthodes analytiques à haute résolution et non-ciblées (masse exacte; n=360 composés) adaptées à l'étude de cellules, - et des méthodes d'étude de flux métaboliques sur culture cellulaire basées sur l'analyse des dérivés de traceurs marqués aux isotopes stables. Le développement de ces méthodes m'a permis d'obtenir les résultats suivants. J'ai démontré l'importance du D-2-HG comme marqueur de la présence de mutations IDH1/2 dans une large cohorte de patients leucémiques, à la fois pour le diagnostic et pour le suivi des patients sous traitement. Notre étude pilote a conduit à utiliser ce paramètre en pratique hospitalière courante dans le laboratoire de chimie analytique de l'institut Gustave Roussy (IGR; Villejuif). L'étude de profils métaboliques associés aux mutations affectant les enzymes IDH2 et succinate déshydrogénase nous a permis d'identifier des mécanismes compensatoires du dysfonctionnement du cycle de Krebs, par exemple la sur-activation de la pyruvate carboxylase. Nous avons par ailleurs montré que ces mécanismes ne sont que partiellement efficaces; ils pourraient ainsi servir de cibles thérapeutiques. Une mutation du gène IDH2 (R140Q) est retrouvée chez des patients atteint de LAM et chez des patients possédant une acidurie D-2-hydroxyglutarique, maladie héréditaire du métabolisme extrêmement rare. Un inhibiteur spécifique de l'enzyme IDH2 possédant la mutation R140Q est actuellement testé comme traitement dans un essai clinique à l'IGR pour les patients leucémiques. Nous avons étudié les effets de ce composé sur des fibroblastes de notre patient atteint d'acidurie D-2-hydroxyglutarique. Nous avons confirmé ses effets sur l'enzyme IDH et observé des effets secondaires sur le métabolisme des lipides et du cycle de Krebs, à la fois dans les fibroblastes témoin et du patient. Cet inhibiteur étant connu pour avoir des effets sur la différenciation cellulaire, nos résultats pourraient permettre d'expliquer les mécanismes impliqués. Ce travail a apporté de nouveaux outils pour l'exploration des maladies métaboliques traditionnelles ainsi que de certains types de cancers, et il met en avant de nouvelles illustrations de la puissance de l'approche métabolique pour identifier des points d'intervention et de surveillance thérapeutique personnalisée des patients ("théranostique"). / The Krebs cycle has a central role in cellular metabolism and is at the junction of many essential pathways. Since 2000, a link has been shown between the development of particular cancers and mutations affecting genes coding for several Krebs cycle enzymes, i.e., succinate dehydrogenase, fumarase or iso-enzymes 1 and 2 of the isocitrate dehydrogenase (IDH). The IDH mutations are found in 15 to 20 % of acute myeloid leukemias and up to 80% of specific gliomas. These mutations affect the enzyme active site and are responsible for an neomorphic activity that is the production and accumulation of a putative oncometabolite : the D stereoisomer of the 2-hydroxyglutarate (D-2-HG) which is linked to energetic and epigenetic deregulations in the cell. To better understand the mechanisms between these abnormalities and human pathology, my PhD work involved the development of different analytical tools : - First of all, a robust method of separation and quantification of the stereoisomers D and L by chiral derivatization of the 2-HG, in tandem mass spectrometry, - GC tandem MS was also used to develop targeted metabolomic methods with high specificity for the analysis of more than 120 compounds of clinical interest, - An analytical non-targeted method using high mass resolution (exact mass; n=360 compounds) adapted to the study of fibroblast cells, - and finally, methods for the study of metabolic flux in culture cell based on derivatives of stable labeled tracers. The development of these methods led to the following results. I highlight the importance of the D-2-HG as a biomarker of the presence of IDH1/2 mutations in a large cohort of leukemic patients, for the diagnostic and the follow-up of patients under treatment. Our pilot study was the starting point for routine usage of this test in the clinical setting at the Institut Gustave Roussy (IGR; Villejuif). The study of metabolic profiles related to the mutations affecting IDH enzymes and succinate dehydrogenase allowed us to identify compensatory mechanisms of the dysfunction of the Krebs cycle, notably, the overactivation of pyruvate carboxylase. Moreover, we have shown that because these mechanisms are only partially efficient; they have potential to provide therapeutic targets. An IDH2(R140Q) mutation is shared between patients with AML and patients with D-2-hydroxyglutaric aciduria, a very rare hereditary disease of the metabolism. A specific inhibitor of the IDH2 enzyme mutant for R140Q is currently used in a clinical trial at the IGR institute. We studied the effects of this compound in fibroblasts of our aciduria patient. We confirmed the expected effect in the IDH enzyme and also observed moderate off-target effects concerning the lipid and the Krebs cycle metabolism, both in control and patient fibroblasts. Because this inhibitor is known to have effects in the cellular differentiation, our results could explain the underlying mechanisms. This work provides new tools for the exploration of traditional inherited metabolic diseases, as well as particular cancers, and illustrates the power of the metabolic approach to identify therapeutic targets and for the personalized monitoring of patients ("theranostics").