Universiẗat, Diss., 2002--Mainz.

Tierärztl. Hochsch., Diss., 2004--Hannover.

Submitted by Amanda Silva (amanda.osilva2@ufpe.br) on 2015-03-05T13:29:04Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO Rafael Thompson de Oliveira Lemos.pdf: 1078520 bytes, checksum: 8a4e2b9b01b627e15dc3df1bd4ca084c (MD5) / Made available in DSpace on 2015-03-05T13:29:04Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) DISSERTAÇÃO Rafael Thompson de Oliveira Lemos.pdf: 1078520 bytes, checksum: 8a4e2b9b01b627e15dc3df1bd4ca084c (MD5) Previous issue date: 2013 / CNPq / O Estuário de Suape está localizado no litoral sul de Pernambuco, Brasil, cerca de 40 km da capital Recife. Este estuário está presenciando um rápido desenvolvimento industrial e portuário nas últimas décadas, com a implantação do Complexo Industrial Portuário de Suape (CIPS). Várias empresas instaladas na região operam cargas com derivados de petróleo, representando uma potencial fonte de hidrocarbonetos para o estuário. Amostras de água e sedimento foram coletadas com o objetivo principal de avaliar a presença de hidrocarbonetos no Estuário de Suape, identificando suas fontes e concentrações, em duas estações do ano (chuvosa e seca). As concentrações de hidrocarbonetos de petróleo dissolvidos e/ou dispersos na água foram determinadas usando a técnica de UV-Fluorescência. Os resultados variaram entre 0,05 e 4,59 μg L-1 equivalentes em óleo Carmópolis e entre 0,01 e 1,39 μg L-1 equivalentes em criseno, sugerindo que a região ainda pode ser classificada como não poluída. Algumas concentrações relativamente altas (>1 μg L-1) estão possivelmente associadas a resíduos originados nas atividades portuárias e do estaleiro, bem como a eventuais descargas industriais e lançamentos de resíduos de óleo por embarcações de pesca ou lazer. As concentrações de hidrocarbonetos de petróleo na água foram significativamente menores durante o período chuvoso, provavelmente devido a maior diluição dos contaminantes causada pelo aumento da precipitação e do fluxo de água doce no Rio Massangana. As concentrações de hidrocarbonetos alifáticos (HAs) foram determinadas no sedimento através da técnica de cromatografia em fase gasosa acoplada a um detector de ionização em chama (GC-FID) e os hidrocarbonetos policíclicos aromáticos (HPAs) foram determinados através de cromatografia em fase gasosa acoplada a um detector de espectrometria de massas (GC-MS). Os HAs variaram entre <LD e 27,15 μg g-1, e as concentrações de n-alcanos (C12-C35) variaram entre <LD e 6,84 μg g-1. Os resultados indicaram que o material orgânico proveniente de plantas superiores foi a principal fonte de hidrocarbonetos alifáticos, porém sinais de óleo degradado também foram observados em alguns sedimentos. As concentrações de HPAs variaram entre 4,25 e 888,42 ng g-1, e são relativamente baixas quando comparadas a estuários cronicamente impactados. As maiores concentrações foram encontradas próximas do quebra-mar na saída sul do estuário e estão provavelmente relacionadas ao transporte dos contaminantes levados pelas correntes para esta área de menor hidrodinâmica, que favorece a maior deposição dos mesmos. Além disto, os processos de dragagem não ocorrem neste local possibilitando um maior acúmulo de contaminantes. Os resultados indicaram que os HPAs encontrados nos sedimentos são provenientes de duas fontes distintas: introdução direta do petróleo e de compostos gerados em processos pirolíticos, através da queima de combustíveis ou matéria orgânica. Concentrações relativamente elevadas foram observadas para alguns HPAs individuais, representando moderada probabilidade em causarem danos à biota local. Este estudo mostra que as atividades desenvolvidas no estuário de Suape associadas à presença de manguezais na região contribuem para a introdução de hidrocarbonetos, mesmo que em baixas concentrações. Entretanto, devido ao crescente desenvolvimento do CIPS, incluindo a refinaria Abreu e Lima que iniciará suas operações em breve, é essencial que um programa de monitoramento contínuo seja implantado.

This diploma thesis addresses the presence and determination of chloramphenicol residues in biological materials. The theoretical part presents the literature retrieval containing information about veterinary medicaments with the banned use in food producing animals and also the sum of the legislative requirements concerning the presence of these substances in foodproducts and raw food materials of animal origin. The comparison was carried out between the existing analytical methods used for the determination of chloramphenicol residues in different biological materials, which are altogether based on the solid phase extraction for the extract cleaning and the new procedures for sample preparations using columns where the sorbent performs on the molecularly imprinted polymers principle.

The thesis is dedicated to the phospholipids and their polar headgroups analysis by gas chromatography, capillary electrophoresis and mass spectrometry. Phospholipids are the most important polar lipids and they are classified into phospholipid classes according to their phosphorylated groups. Phospholipids can be found in cell membranes and the changes in their ratio are monitored to research the impact of external conditions on cells. Actually thin layer chromatography is still used for phospholipid class ratio analyses. It is not suitable for microbiological research due to its time demandingness. The presented compendium of papers engaged in phospholipid classification is targeted on Bacillus subtilis strain, which produces potential antibiotics with detergent effect - surfactin. Published methods can be used for research of optimal conditions for producing microbe cultivation. Because non-polar parts of the phospholipid molecule (fatty acids) can affect the analysis methods on spliced polar headgroups have to be designed. Capillary electrophoresis and gas chromatography methods were developed and the latter one was further optimized for simultaneous analysis with fatty acids. Additional part deals with an alternative approach which consists in direct injection on mass spectrometer of intact...

In aroma analysis, strawberries have always been the favored fruit because of their relatively high content of typical and pleasant aroma constituents. Esters, aldehydes, alcohols and sulfur compounds have been found to be the main aroma components in strawberry. In recent years, two volatile compounds, 2,5-dimethyl-4-methoxy-3(2H)-furanone (DMF) and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DHF) were reported to contribute heavily to strawberry aroma. These two compounds have been found in all wild strawberries studied, but found only in few cultivated varieties. In this work, three kinds of cultivated strawberries were sampled and analyzed. The three strawberries all belong to the Camarosa variety. They came from different growing areas: Salinas (California), Orrville (Ohio), and Memphis (Tennessee). The volatile compounds of these three strawberries were separated by Gas Chromatography (GC), and identified by Mass Spectrometer Detector (MSD). Column and experimental conditions were optimized for this particular separation. Salinas, Orrville and Memphis strawberries have very similar aroma constituents, however, in slightly differing amounts. Several unique peaks were found in each strawberry, which may well account for the differences in the aroma qualities of the three. 2-Furaldehyde was found in both Memphis and Orrville strawberries, but not in Salinas. It is a key odor compound correlated with woody aroma and it has a low odor threshold value. These two properties make it contribute negatively to the pleasant aroma of Memphis and Orrville strawberries. A compound, 2-furanmethanol, was found only in Salinas strawberries. This compound has a faint burning aroma, however, its high odor threshold value offsets its potentially bad aroma. DMF was found in all three strawberries, but no DHF was detected in any of the three. We propose a possible explanation for the absence of DHF. Ethyl (methylthio) acetate, which is a sulfur-containing compound, was found in both Orrville and Salinas strawberries. This work is the first to report its presence in strawberries of any variety. An external standard method was employed to quantify seven main aroma components found in the strawberry extracts. Aroma values were introduced and then calculated together with sensory descriptions of these compounds. Salinas strawberry was found to have the best aroma quality of the three. These results indicate that the odors of strawberries of the same variety can be different when grown in different geographical areas. / Master of Science

Indiana University-Purdue University Indianapolis (IUPUI) / Gas Chromatography/Mass Spectrometry (GC/MS) is an analytical technique that sees frequent use in labs across the world. It is also one of the most common instruments found in forensic science laboratories. This technique can efficiently and accurately separate and identify a broad range of compounds that may be present in evidence submitted for analysis. In this work, the versatility of this instrument was applied to new methodologies for the detection of explosives and illicit drugs. The analysis of explosives by GC/MS is common but can be problematic. The thermally sensitive nature of some explosives can cause them to degrade when introduced to the high temperatures of a GC/MS inlet. This project looked at the design and implementation of a way to separate and detect a variety of nitrate ester explosives in a short amount of time. In addition to this, a new technique known as Total Vaporization-Solid Phase Microextraction (TV-SPME) was utilized as a pre concentration technique. The parameters for TV-SPME were statistically optimized for a low level of detection. The combination of these areas allowed for the separation of ethylene glycol dinitrate, nitroglycerin, erythritol tetranitrate, and pentaerythritol tetranitrate with a detection limit as low as 50 parts per trillion (ppt). Degradation products such as 1-mononitroglycerin, 1-3-dinitroglycerin, and 2-mononitroglycerin were also successfully identified. The problem of thermally labile compounds extends to the world of illicit drugs. In the second project, several derivatization schemes were developed for common controlled substances. N,O-Bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS) was used for silylation, trifluoroacetic anhydride (TFAA) was sued for acylation, and (N,N-Dimethylformamide dimethyl acetal (DMF-DMA) for alkylation. Three different compound classes totaling 15 different drugs were investigated. N,N-Dimethylformamide dimethyl acetal (DMF-DMA) is presented as a novel way of derivatizing several drugs of interest. Primary amines and zwitterions were derivatized with this reagent to much success, specifically: amphetamine, 2-(4-Iodo-2,5-dimethoxyphenyl)ethan-1-amine (2C-I), pregabalin, and gabapentin.

Widespread sedentary lifestyle and unhealthy eating habits in the last few decades have resulted in a dramatic increase of the number of people affected by obesity, type 2 diabetes, and cardiovascular diseases. The study of these pathological conditions revealed that impaired metabolism often causes these disorders. Lipid metabolism research has contributed significantly to determining mechanisms underlying metabolic disorders. Omega-3 fatty acids are an interesting target for lipidomics studies because they were shown to lower risk of cardiovascular diseases and are hypothesized to regulate lipid metabolism. In this work, I optimized lipid extraction and chemical modification methods for analysis of fatty acids profile of tissue samples and biofluids using comprehensive two-dimensional gas chromatography coupled to mass spectrometry (GCxGC-MS). At first, I evaluated the relative amount of omega-3 fatty acids in red blood cells (Omega-3 index) of people living in Czech Republic in either the capital city (n=476) or the rural region (n=388). For this large-scale project, I extracted phospholipids from red blood cell (RBC) membranes, transesterified them into fatty acid methyl esters (FAMEs), and measured their profile by GCxGC-MS. The mean Omega-3 index was 3.56 mol % and I detected no significant...

Highly oxygenated compounds in bio-oil produce negative properties that have hampered fuel development. Copyrolysis with plastics has increased hydrogen content in past research. Py-GC/MS analyses for two wood types (pine and oak) and three plastic types (polystyrene, polypropylene and high density polyethylene) established temperature, heating rate and residence time to produce a typical bio-oil. Analysis of various plastics to wood ratios by Py-GC/MS showed that a 50:50 wt/wt ratio produced the highest level of low molecular weight compounds best for fuel viscosity. Copyrolysis was performed on a laboratory-scale reactor at these temperature and wood-to-plastic ratios. Copyrolysis lowered bio-oil oxygen content and increased carbon content. Lower water content, acid value and viscosity also resulted, improving bio-oil suitability for fuels. Cross reactions between wood and plastics formed no new chemical species during copyrolysis. These results indicate that copyrolysis of waste plastics with woody biomass has potential for improving bio-oil properties for fuels production.

Vine tea (Ampelopsis grossedentata) is a Chinese herbal tea, rich in the natural antioxidant dihydromyricetin, that has multiple health properties and potential food and beverage applications. However, there is little information available on vine tea aroma, color and sensory characteristics. In this study, volatile components of vine tea infusions were identified by headspace solid-phase micro-extraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). Commercial vine teas samples were brewed with distilled water and Blacksburg (VA, USA) tap water and analyzed in triplicate. Vine tea infusions had acidic pH values and dark, reddish-yellow color. Type of water and vine tea sample both affected the overall volatile chemical composition of vine tea infusions. A total of fifty-six volatile components were identified in vine tea infusions. However, only seven aldehydes (hexanal, (E)-2-hexenal, (Z)-4-heptenal, nonanal, (E,Z)-2,4-heptadienal, (E,E)-2,4-heptadienal, and β-cyclocitral), two ketones (6-methyl-5-hepten-2-one and β-ionone), and one alcohol (1-penten-3-ol) were identified in more than 90% of all vine tea infusions (n=54). Results of this study may help further investigations in chemical and sensorial characteristics of vine tea, and the development of new healthy products. / Master of Science in Life Sciences