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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.
121

Molecularly imprinted polymers as selective sorbents for recognition in complex aqueous samples / Polymères à empreintes moléculaires en tant qu’adsorbants sélectifs pour la reconnaissance dans des milieux aqueux complexes

Nestora, Sofia 13 April 2017 (has links)
Dans cette thèse, nous avons démontré la faisabilité de la préparation de polymères à empreinte moléculaires (MIP) hautement sélectifs pour la reconnaissance dans des matrices aqueuses complexes avec des applications dans les cosmétiques et en technologie alimentaire. Les MIP (de l'anglais molecularly imprinted polymers) sont des récepteurs synthétiques comparables aux anticorps, qui sont synthétisés par co-polymérisation de monomères fonctionnels et réticulants en présence d'un gabarit moléculaire. Leurs propriétés de reconnaissance moléculaire, associées à leur grande stabilité, robustesse mécanique, faible coût et leur synthèse facile les rendent extrêmement intéressants comme matériaux de capture sélective, avec des applications dans les séparations analytiques, la détection et la vectorisation des médicaments. Cependant, leur reconnaissance sélective dans des milieux aqueux reste toujours problématique et c'est l'une des raisons de leur expansion commerciale restreinte. Dans une première partie, nous avons développé un MIP fonctionnant en milieu aqueux pour son application comme ingrédient actif dans un déodorant. Les odeurs corporelles sont principalement dues à des acides gras volatils générés à partir de leurs précurseurs, des conjugués de glutamine par des enzymes hydrolytiques produites à partir de bactéries présentes sur la peau. La plupart des anti-transpirants et des déodorants actuellement commercialisés contiennent des sels d'aluminium et des agents antibactériens non spécifiques, respectivement. Cependant, l'utilisation extrêmement étendue de ces produits nécessite des solutions alternatives en ce qui concerne divers problèmes (environnement, respect de l'écosystème de la peau, toxicité, etc.). Pour cette raison, un MIP a été synthétisé pour capturer les précurseurs conjugués de glutamine afin qu'ils ne soient plus disponibles aux bactéries, empêchant ainsi leur transformation en composés malodorants. Afin de générer des liaisons sélectifs dans des environnements aqueux, un monomère à base d'amidinium qui peut former une interaction électrostatique stoechiométrique forte avec les groupes carboxyle sur le gabarit moléculaire a été synthétisé. Le MIP, mélangé dans une formulation dermo-cosmétique, pourrait capter sélectivement les précurseurs conjugués de glutamine, au milieu d'une multitude d'autres molécules présentes dans la sueur humaine. En outre, le MIP n’affecte pas les bactéries de la peau, ouvrant la voie à des déodorants innovateurs de nouvelle génération, moins problématiques pour la santé. Dans une deuxième partie, nous avons développé une procédure rapide et efficace basée sur l'extraction en phase solide à empreinte moléculaire (MISPE) pour la purification sélective de la bétanine et de son stéréoisomère l’isobétanine à partir d'extraits de betterave. La bétanine est un pigment naturel ayant un fort pouvoir antioxydant et dont les propriétés pharmacologiques sont de plus en plus étudiées. Ce pigment est actuellement utilisé comme simple colorant alimentaire. Dans notre étude, l'acide dipicolinique a été utilisé comme gabarit moléculaire pour la synthèse de MIP, en raison de sa similarité structurelle avec le groupe chromophore de la bétanine. Les procédures MISPE ont été optimisées permettant l'élimination presque complète des glucides issus de la matrice végétale ainsi que la majorité des protéines, ce qui permet d'obtenir un rendement élevé d'extraction de la bétanine / isobétanine en une seule étape. De plus, toute la procédure d'extraction a été réalisée dans des solvants respectueux de l'environnement, tels que l'éthanol ou l'eau. Pour conclure, nous sommes convaincus que ce travail pave le chemin au développement d'une nouvelle génération des MIP fonctionnant en milieu aqueux avec des propriétés de reconnaissance améliorées dans des environnements complexes, qui pourra s'appliquer également à d'autres domaines biotechnologiques et biomédicaux. / In this thesis, we have demonstrated the feasibility of preparing highly selective molecularly imprinted polymers (MIPs) for recognition in complex aqueous matrices with applications in cosmetics and food technology. MIPs are synthetic tailor-made receptors, with binding affinities and specificities comparable to those of natural antibodies. Their molecular recognition properties, combined with their high stability, mechanical robustness, low cost and easy synthesis make them extremely attractive as selective capture materials with applications in analytical and preparative separations, sensing and drug delivery, among others. However, their selective recognition in aqueous samples still remains problematic and is one of the reasons for their so far lilited commercial expansion. In the first part, we developed a water compatible MIP for its application as an active ingredient in a deodorant. Body odors are mainly due to volatile fatty acids generated from their glutamine conjugate precursors by hydrolytic enzymes from bacteria present on the skin. Most currently marketed anti-perspirants and deodorants contain, respectively aluminum salts and unspecific antibacterials. However, the extremely wide use of these products requires alternative solutions with regard to various problems (environmental, respect of skin ecosystem, toxicity, etc.). For this reason, a MIP was developed to capture the glutamine conjugate precursors so that they are no longer available to the bacteria, thus preventing their transformation to malodorous compounds. In order to generate binding selectivity in aqueous environments, an amidinium-based monomer which can form a strong stoichiometric electrostatic interaction with the carboxyl groups on the template, was synthesized. The MIP, blended in a dermo-cosmetic formulation, could capture selectively the glutamine precursors, amidst a multitude of other molecules present in human sweat. Furthermore, the MIP did not affect the skin bacteria, paving the way to an innovative and 'safer ' future-generation deodorant. In the second part, we developed a fast and efficient procedure based on molecularly imprinted solid­ phase extraction (MISPE) for the selective clean-up of betanin and its stereoisomer isobetanin from red beetroot extracts. Betanin is a natural pigment with significant antioxidant and biological activities currently used as food colorant. Dipicolinic acid was used as template for the MIP synthesis, because of its structural similarity to the chromophore group of betanin The MISPE procedures were optimized allowing the almost complete removal of carbohydrates and the majority of proteins, resulting in high extraction recovery of betanin / isobetanin in a single step. Moreover, the whole extraction procedure was performed in environmentally friendly solvents with either ethanol or water. To conclude, we believe that this study paves the way towards the development of a new generation of water compatible MIPs with improved recognition properties in highly complex aqueous environments, and should be applicable to other biotechnological and biomedical areas as well.
122

Développement des méthodes analytiques pour la détection et la quantification de traces des HAP et de pesticides dans l'eau : application à l'étude de la qualité des eaux libanaises

Kouzayha, Abir 08 December 2011 (has links)
La pollution des eaux est particulièrement problématique pour les pays industrialisés et les pays en développement. Des suivis environnementaux se sont alors avérés nécessaires afin de progresser dans la compréhension des origines et des conséquences de la présence de ces polluants. Parmi les polluants organiques les plus dangereux, les Hydrocarbures Aromatiques Polycycliques (HAP) et les pesticides qui peuvent se retrouver à l’état de traces dans les milieux aquatiques. Leur analyse nécessite des méthodes analytiques à la fois spécifiques et sensibles. L’Extraction sur Phase Solide (SPE) suivi d’une analyse par la Chromatographie Gazeuse couplée à la Spectrométrie de Masse (GC-MS) est la méthode la plus couramment employée. Les travaux de thèse s’inscrivent ainsi dans l’optique généralevisant à développer des nouvelles méthodes analytiques pour l’extraction et l’analyse de cesdeux familles de polluants organiques présents dans l’eau. Afin de pallier les contraintes classiques de la SPE, une nouvelle approche a été développée qui consiste à introduire latechnique de centrifugation dans certaines étapes de la procédure SPE. La nouvelle méthodeélaborée a permis de réduire considérablement le temps de préparation et d’économiserl’utilisation et le rejet des solvants organiques, en réduisant presque 10 fois les volumes nécessaires à l’obtention des rendements de récupération satisfaisants. Une méthoded’analyse par injection à température programmable (PTV) a été optimisée afin d’améliorerles seuils de détection des HAP. Cette étude a permis également d’avoir les informations surla qualité des eaux de pluie, eaux souterraines et eaux de surface au Liban quant au niveau deleur contamination pour les HAP et les pesticides. / Water pollution presents a very critical problem facing industrial and developping countries. The environmental monitoring of the contaminants seems necessary to understand their sources and impacts. Among a wide variety of organic pollutants present in water,polycyclic aromatic hydrocarbons (PAHs) and pesticides are of particular importance as widespread, persistent, and toxic contaminants. They are usually present at trace levels in theacquatic surfaces; therefore their detection and control require selective and sensitiveanalytical procedures. The Solid-Phase Extraction (SPE) followed by the Gas-Chromatography coupled to Mass Spectrometry (GC-MS) are the most commonly usedtechniques for their analysis in water. Thesis objectives are focused on the development of new analytical methods for the extraction and analysis of these two families of pollutants present in water. To overcone the contraints of the traditional SPE, a new approach was developed consisting on the introduction of the centrifugation in several steps of the procedure. The new method showed practical environmental and economical advantages interms of sample preparation time, simplicity, reduction in solvent use, and cost and isparticularly suitable for routine applications requiring a high sample throughput. Aprogrammed temeperature vaporizing (PTV) injection method was also optimized and validated in order to improve the detection limits for the GC-MS analysis of PAHs. The evaluation of the quality of different water systems in Lebanon including rainwater,groundwater, drinking water and surface water was accomplished in this study.
123

Paper Spray - Mass Spectrometry: Investigation of Sampling Devices for Illicit Drug Detection and Quantification

Nguyen, Chau Bao 07 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Paper spray - mass spectrometry (PS-MS) has been developed as a rapid and direct ionization method for qualitative and quantitative analysis of complex samples at trace levels. In this work, different sampling devices for PS-MS were investigated to improve the assay’s simplicity and sensitivity over traditional approaches. In particular, chapter two characterizes an alternate paper substrate to enhance drug detection on surfaces like asphalt, cloth, concrete, aluminum, and glass. Analysis occurs on a single spray ticket coated with pressure-sensitive adhesive (PSA), also known as Post-it notes to detect and quantify drug residues. A PS-MS method utilizing PSA paper was developed to detect a mixture of ten drugs off of various surfaces to evaluate the qualitative and quantitative capabilities of the aforementioned substrate. After the method development on a conventional linear ion trap mass spectrometer, the assay was translated for use on a portable mass spectrometer to evaluate the suitability of the pressure-sensitive adhesive paper substrate in the field in chapter three. Chapter four introduces a sampling device combined with a snap-in solid-phase extraction (SPE) column. The new cartridge design not only inherits the functions from the first iteration SPE cartridge, including extraction and preconcentration from complex samples, but also exhibits greater flexibility in volume control and ease of use for on-site sample collection.
124

Hormony v čistírenských kalech / Hormones in sewage sludge

Jagošová, Klára January 2018 (has links)
Currently there is a spate of interest in the presence of pharmacologically active substances in the environment. These substances are excreted in active or metabolized form and with wastewater pass the wastewater treatment plant. Current treatment technologies do not always eliminate all pharmaceuticals effectively and therefore they enter the environment. One of these active groups is the group of steroid hormones. Steroid hormones belong to the group of endocrine disruptors and they are considered to be dangerous for the ecosystems. Due to the hydrophobic character of steroid hormones they undergo partial or total sorption from wastewater to sludge. Sewage sludge is the by product of wastewater treatment and contains heavy metals, organic contaminants and pathogenic bacteria. A part of produced sewage sludge is used as a fertilizer in the Czech Republic. This issue follows the regulation 347/2016 – conditions of agricultural use of sewage sludge. Waste policy of EU will alter the conditions of sludge disposal, so it is necessary to obtain data about the concentration levels, fate and behaviour of those pollutants. This thesis was focused on five natural female hormones and four synthetic, which are used as a part of contraceptive pills and substitutional hormonal therapy. Determination of hormones was performed in four steps including ultrasonic assisted extraction, clean up by solid phase extraction, derivatization and final analysis by gas chromatography with mass spectrometry on triple quadrupole in MS/MS mode.
125

Stanovení karnitinu v potravních doplňcích / Determination of carnitine in food supplements

Buchtová, Zuzana January 2008 (has links)
This work deals with the determination of L-carnitine in food supplements. L-carnitine is a substance naturally occurring in organism, essential for metabolism of fatty acids. In food supplements is used especially for reducing body weight as a "fat burner". L-carnitine is popular with athletes for improve athletic performance. While data are not available to support these positive effects of carnitine, the positive results of carnitine supplementation in the medicine were found, mainly on cardiovascular system. The literary part of this study describes the properties and the use of carnitine in the diet of human. Furthermore, a review of methods used for determination of L-carnitine in variety of samples is mentioned. In the experimental section the efficiency of SPE method for preparation matrix of real samples was investigated. A cation exchange solid phase extraction seems to be the most effective. The optimal conditions for isolation of L-carnitine by SPE extraction were not developed. L-carnitine was determined in six various food supplements by reverse phase chromatography with UV/VIS detection.
126

Stanovení vybraných pesticidů pomocí plynové chromatografie / Assessment of selected pesticides using gas chromatography

Matušková, Monika January 2012 (has links)
The submitted thesis deals with determination of selected pesticides in water samples by gas chromatography. The target pesticides belong to the group of organophosphates (chlorpyrifos, diazinon, parathion, dimethoate, phosmet) and carbamates (carbofuran, aldicarb, methiocarb, pirimicarb, and propamocarb). In the theoretical part, the division of pesticides is stated, and their properties are described, as well as their fate in the environment and their negative effects. Then, the possibilities of analytical determination based on gas chromatography are characterized. The experimental part describes the treatment of the samples and their subsequent analysis. Solid phase extraction was chosen as the extraction technique. Two kinds of cartridges were optimized (Oasis HLB and Supelclean ENVI-18) in combination with various elution reagents. The most suitable combination was then used for processing of real samples of waste-water, which was taken from WWTP in Brno Modřice. For the final determination of the target compounds by gas chromatography, two types of detectors were used: mass spectrometer and an electron capture detector.
127

Stanovení léčiv v pitných vodách metodou HPLC / Determination of pharmaceuticals in drinking waters using HPLC

Králová, Radka January 2015 (has links)
The aim of the diploma thesis is the determination of macrolide antibiotics in drinking water by using of high performance liquid chromatography. Erythromycin and clarithromycin were selected such as representative macrolides due to frequently prescribed pharmaceuticals in this time. Solid phase extraction (SPE) by using of Oasis HLB cartridges was applied for pre concentration and purification of chosen analytes in real samples of drinking water. Optimalization of method and analysis were performed by using of high performance liquid chromatography with mass spectrometry detection (HPLC-MS). The suitable method was selected for determination of macrolides in real samples taken from two sources of drinking water, the interception of water in Litovel and Černovír Olomouc.
128

Využití kapilární zónové elektroforézy pro stanovení vybraných analgetik ve vodách / Use of Capillary Zone Electrophoresis for Determination of Selected Analgetics in Water

Čapka, Lukáš January 2011 (has links)
From viewpoint of environmental analysis in the whole world became popular in the latest years the question of drugs’ breakthrough to the component of environment. These contami-nants belong to the biological active compounds, with different physical-chemical and biolog-ical properties and evince great tendency to bioaccumulation. They penetrate to the environ-ment because of their increasing of usage and wrong techniques of liquidation. The most often use drugs are preparations against pain – analgetics, and from this category there are non-steroidal anti-inflammatory drugs. The frequent usage of this compounds relate to their easy accessibility. From this large group of compounds was chosen for monitoring: diclofenac, ibuprofen, ketoprofen, salicylic acid, naproxen and acetaminophen; because they include in favorite preparations. The monitoring matrix was the wastewater from two waste water treat-ment plants (WWTP). The sampling was performed in inflow and outflow because the com-paring of concentration of selected contaminants and discovering of efficiency of removing the polutants reliance on treatment technology. For extraction of selected contaminants was used solid phase extraction (SPE) and for determination was used capillary zone electrophore-sis (CZE) with diode array detection (DAD). There was identified and quantified all of se-lected analgetics in inflow and so in outflow of WWTP. That means, this polutants infuse into surface water and then into other components of environment.
129

Vliv technologických procesů na obsah prioritních kontaminantů v čistírnách odpadních vod / Influence of technological processes on the content of priority contaminants in wastewater treatment plants

Mikulíková, Iva January 2016 (has links)
Water is one of the most abundant substances on Earth and it is an essential part of our lives. Its pollution has an impact on the whole ecosystem. Polybrominated diphenyl ethersare synthetic persistent organic pollutants used as flame retardants in various commercial and household products. This thesis is focused on assesing the degree of elimination of PBDEs in wastewater treatment plants with different technological processes of purification. The samples were collected in the three wastewater treatment plants in the south-moravian region, that means WTP Brno – Modřice, WTP Mikulov and WTP in VFU Brno.
130

Stanovení makrolidů v odpadních vodách v průběhu technologií aplikovaných na čistírnách odpadních vod / Determination of macrolides in wastewater during the technology applied to wastewater treatment plants

Landová, Pavlína January 2016 (has links)
Diploma thesis is focused on determination of macrolide antibiotics in wastewater. Environmental contamination with drugs currently represents a major problem. To determine the level of contamination is necessary to develop the appropriate analytical techniques. From the group of macrolide antibiotics were selected four representatives: erythromycin, clarithromycin, azithromycin and roxithromycin due to their frequent use in Czech Republic. For their isolation from wastewater was selected solid phase extraction and for analysis high performance liquid chromatography with mass spectrometric detection was chosen. Under optimized conditions, the ten days analysis of wastewater from the WWTP Brno-Modřice, two days analysis of wastewater from the WWTP Mikulov and one day analysis of wastewater from WWTP of University of Veterinary and Pharmaceutical Sciences Brno was performed.

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