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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Identifizierung und Quantifizierung von Verbindungen mit östrogener Wirkung im Abwasser

Spengler, Peter. January 2001 (has links)
Stuttgart, Univ., Diss., 2001.
22

Entwicklung und Anwendung von Methoden zur Erfassung von Pyrrolizidinalkaloiden in Honig und Pollen

Kempf, Michael January 2009 (has links)
Würzburg, Univ., Diss., 2009. / Zsfassung in engl. Sprache.
23

Amino acid analysis in biological fluids by GC-MS

Kaspar, Hannelore January 2009 (has links)
Regensburg, Univ, Diss., 2009.
24

Identifizierung und Quantifizierung von Verbindungen mit östrogener Wirkung im Abwasser

Spengler, Peter. Unknown Date (has links) (PDF)
Universiẗat, Diss., 2001--Stuttgart.
25

GC/MS-Meßsystem für Nicht-Methan-Kohlenwasserstoffe Spurengasuntersuchungen im Tropopausenbereich und in der maritimen Grenzschicht /

Mühle, Jens. Unknown Date (has links) (PDF)
Universiẗat, Diss., 2002--Mainz.
26

Untersuchung zur Pharmakokinetik des Arzneistoffes Dembrexin hinsichtlich der Dopingrelevanz beim Pferd

Massmann, Susanne. Unknown Date (has links) (PDF)
Tierärztl. Hochsch., Diss., 2004--Hannover.
27

Origem e distribuição de hidrocarbonetos no estuário de Suape - PE

Lemos, Rafael Thompson de Oliveira 31 January 2013 (has links)
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.
28

Stanovení reziduí chloramfenikolu v biologickém materiálu, vodě a krmivech metodou GC/MS / The assesment of chloramphenicol residues in biological material, water and feed by GC/MS

Lukačková, Dagmar January 2009 (has links)
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.
29

Analýza biologicky aktivních látek moderními separačními metodami / Analysis of biologically active substances by modern separation methods

Bierhanzl, Václav January 2018 (has links)
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...
30

Analysis of Aroma Constituents in Cultivated Strawberries by GC/MS

Song, Xiling 08 June 1999 (has links)
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

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