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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.
251

Matéria orgânica pirogênica e gênese das Terras Pretas de Índio no município de Iranduba - AM / Pyrogenic organic matter and Amazon Dark Earth genesis in the county of Iranduba, Amazon State, Brazil

Santos, Taís Almeida 27 January 2016 (has links)
Solos com horizonte A escurecido, com presença de artefatos humanos como cerâmicas, ossos e/ou conchas, alta saturação por bases, carbono orgânico e carvões são denominados comumente de Terras Pretas de Índio (TPI), de ampla ocorrência na região Amazônica. Tais características tornam estes solos muito favoráveis para o cultivo agrícola, sobretudo pelo elevado conteúdo de matéria orgânica do solo (MOS). No entanto, dentre as questões ainda não desvendadas quanto à gênese destes solos, está a natureza e mecanismos de retenção desta matéria orgânica nas TPI. Nesse sentido, o objetivo deste trabalho foi elucidar a natureza química da MOS em solos com horizonte A antrópico e em solos de referência (sem horizonte A antrópico). Para isso, dois perfis de TPI e um perfil de referência foram selecionados na área do Campo Experimental do Caldeirão no município de Iranduba - AM. Amostras de todos os horizontes foram coletadas e submetidas ao fracionamento físico e químico da matéria orgânica, gerando as frações: i) (FLL); ii) Leve oclusa (FLO); iii) extraível com NaOH (EX) iv) Resíduo (RES). Todas elas foram caracterizadas por meio da pirólise CG/EM. A FLL e EX estão presentes em quantidades maiores nas TPI, devido, respectivamente, ao maior imput de mateiral fresco promovido intencionalmente pelo homem nestas áreas e à maior humificação deste material. Por outro lado a FLO foi maior no perfil de referência. A FLL possui alta expressão da liteira, sendo constituída, sobretudo por materiais vegetais e carvões. A FLO teve alta variabilidade composicional, no entanto de modo geral possui semelhança com a FLL, mas é menos enriquecida em derviados do BC (compostos poliaromáticos) e maior quantidade de material vegetal fresco (ligninas). No entanto, esta fração contribui muito pouco para o carbono total do solo. Entre os diferentes perfis, a principal diferenciação ocorreu na FLL, que possuiu menos levoglucosan e mais poliaromáticos nos perfis antrópicos, o que mostra, portanto, condições mais avançadas de mineralização e enriquecimento relativo em BC. No entanto, no geral há maior abundância de compostos aromáticos nos perfis de TPI, demonstrando maior contribuição de BC. A fração do resíduo mostrou, grande contribuição de compostos alifáticos. No entanto quando compara-se os diferentes perfis, as TPI são enriquecidas com compostos poliaromáticos, reforçando novamente a contribuição do BC. Não foi possível, com os métodos de extração e fracionamento utilizados, afirmar se os produtos derivados do BC nesta fração estão realmente ligados a fração mineral ou estão presentes no RES por serem insolúveis em alcalino. Nesse sentido, conclui-se que há uma grande contribuição do BC para a estabilização (pelo mecanismo da recalcitrância química) da MO nos perfis de TPI nas diferentes frações e, além disso, verificou-se também nestes perfis estágios mais avançados de decomposição, concordando com o fato de que nas TPI há um maior grau de humificação da MO. / The Anthrosols known as Amazon Dark Earths (ADE) are peculiar soils found in Amazonian Forest, presenting dark coloured A horizons that combine the following features: presence of human artefacts, bones and shells; high levels of organic carbon and coal; and a high base saturation index. Such characteristics are an advantage for agriculture practices, even in the current days. However, their genesis mechanisms are still poorly understood, especially the processes related to organic matter fixation. This contribution aims to elucidate the chemical nature of soil organic matter (SOM) in some Anthrosols and reference soils (without Anthropic A horizons), comparing two pedons with the referred characteristics in the county of Iranduba (Amazon State, Brazil). Soil samples were physically and chemically fractioned, into the following groups: i) FLL, ii) light occluded (FLO), iii) NaOH extractable (EX); iv) residual (RES). SOM samples were chemically characterized using the CG/EM pyrolysis technique. The FLL and EX fractions are more common in IDA soil samples due to the high inputs of fresh plant materials intentionally introduced by human groups in the past, and to the high degree of humification. The FLO fraction was higher in the reference soil samples (without Anthropic A horizons). The FLL fraction was more expressive in the litter samples, consisting of plant materials and coal. The FLO fraction presented a high compositional variability but similar to FLL fraction, less enriched in polyaromatic compounds (BC) and fresh plant materials (lignin). Nevertheless, this fraction represents a minor contribution to total organic carbon of soils. Within the different pedons, the main difference was observed in the FLL fraction, less enriched in levoglucosan and polyaromatic compounds in the Anthrosols. It suggests a rapid mineralization of organic matter and high contribution of BC compounds in these soils. In general, the BC compounds are a major control in Anthrosols. The residual fraction shows high levels of aliphatic compounds. However, in the Anthrosols the BC compounds maintain a high level. It was not possible to determine whether the BC bearing compounds are bound to the mineral fraction or belong to RES fraction (low solubility in high pH values). The BC compounds must contribute significantly to SOM stabilization in the different fractions of Anthrosols pedons (chemical recalcitrance mechanism). Moreover, decomposition degree of SOM is higher in the Anthrosols, in agreement to the high degree of humification.
252

The Detection of an Invasive Pathogen through Chemical and Biological Means for the Protection of Commercial Crops

Simon, Alison G 22 September 2017 (has links)
Standoff detection of targets using volatiles is essential when considering substances that are hazardous or dangerous, or for which the presence or location is unknown. For many invasive biological threats, their presence is often not realized until they have begun visibly affecting and spreading through crops or forests. The fungus Raffaelea lauricola is a biothreat vectored by the invasive beetle Xyleborus glabratus, or redbay ambrosia beetle (RAB), whose presence in avocado groves is currently detectable by visual inspection. Once visually identified, the affected trees must be removed and destroyed to protect those remaining trees. However, if the fungus is identified via standoff volatile detection, there is anecdotal evidence that it can be treated with propiconazole and saved from progression to the fatal laurel wilt disease. As a result of the rapid spread of R. lauricola and the quick death of trees, early detection through standoff methods is essential. The only current method of pre-symptomatic identification is canine detection. Canines are sensitive and selective biological detectors that can trace odors to their source, despite the presence of a variety of background odors. The present research evaluated the volatile organic compounds (VOCs) of the laurel wilt disease and R. lauricola using headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). Additionally, a new method for odor collection and presentation to trained detection canines was developed. Knowledge of the disease and standoff volatile detection capabilities are improved using this information.
253

Tentative Identification of Hydroxylated 2,2',3,5',6-pentachlorobiphenyl Metabolites in Whole Poplar Plants by a Combination of Chromatographic and Spectrometry Techniques

Ma, Cunxian 01 May 2014 (has links)
2,2',3,5',6-pentachlorobiphenyl (PCB95) is a chiral congener of the persistent organic pollutants (POPs) family of PCBs. It has been shown that chiral PCBs can be enantioselectively transformed into hydroxylated metabolites by cytochrome P450 in animals. Previous studies in our group suggested that PCB 95 can be enantioselectively translocated and metabolized in whole poplar plants. In this work, healthy whole poplar plants were hydroponically exposed to PCB95 for 30 days. Two unknown OH-PCB95 metabolites were detected in the roots by HPLC-MS. Different chromatographic and spectrometry techniques, including HPLC-MS, NMR and GC-MS, were tried to determine the structure of the more abundant metabolite of the two. It was identified to be 4'-OH-PCB95 (4'-95) by GC-MS method. The data show that PCB95 can be transformed into at least two hydroxylated metabolites by whole poplar plants, with one of them being 4'-95. Chiral analysis of 4'-95 by HPLC-MS showed slightly more abundance of the second eluting enantiomer E2-4'-95 in the roots, suggesting that the biotransformation of PCB95 to 4'-95 is enantioselective. Comparison with animal studies shows a distinct metabolite profile in whole poplar plants.
254

A Chemical Investigation of New Zealand Unifloral Honeys

Senanayake, Mahima January 2006 (has links)
The diethyl ether-extracted organic compounds of 155 samples of unifloral grade New Zealand kamahi and honeydew honeys, and New Zealand and Norwegian erica honeys, together with a series of active and inactive manuka honeys were analysed using combined gas chromatography/mass spectrometry. It was found that Kamahi honey is characterized by the presence of 2,6-dimethylocta-3,7-diene-2,6-diol, meliracemoic acid, and kamahines A-C and these compounds were typically present at average levels of 31, 14, and 73 mg/kg of honey, respectively. 2,6-Dimethylocta-3,7-diene-2,6-diol was isolated and the structure of this compound was defined using one- and two-dimensional NMR analyses. The only recognizably distinct peak present in the honeydew honey profile was indole acetic acid. In this honey, a relatively low to moderate level of indole acetic acid, ranging from 0.9 to 9.1 mg/kg honey was detected. In the New Zealand erica honey samples, ericinic acid, isoericinic acid isomers (average levels 363 and 34 mg/kg respectively), trans,cis and trans,trans-abscisic acid isomers (average levels 302 and 224 mg/kg respectively) and benzoic acid (average level 6950 mg/kg) were identified as floral marker compounds. Ericinic acid was isolated and the structure of this acid was defined using one-and two-dimensional NMR analyses. Low levels of ericinic and isoericinic acids (average levels of 1.1 and 0.32 mg/kg respectively) were detected in the Norwegian erica-rich honeys. The results presented here indicate that ericinic and isoericinic acids are likely to be universally present in erica honeys at levels which may range from as low as 1 mg/kg or less, as found in some Norwegian samples, to more than 100 mg/kg in some New Zealand samples. Two groups, namely a fingerprint pattern which characterized active manuka honeys, and a fingerprint pattern that characterized inactive manuka honeys were identified. Some substances contributing to the GCMS profile were found as marker compounds for the presence of unidentified substances responsible for the UMF activity. A statistically significant correlation was found between a small set of marker compounds (i.e. phenylacetic acid, 2-methoxyacetophenone, 2-methoxybenzoic, phenyllactic, octanedioic, cis-cinnamic, trans-cinnamic, nonanedioic, 4-methoxyphenyllactic and decanedioic acids and methyl syringate) and UMF activity of manuka honey. The best-fit marker compound regression equation (R = 0.92) was obtained for a set of pooled 30 moderate to high activity (UMF gt 14.1) samples. It was shown that the marker compound regression equation is capable of predicting the approximate UMF activity in both active and inactive manuka and kanuka honey samples. The leaf oil profiles of manuka (L. scoparium) plants that yielded active and inactive manuka honeys were characterized using an adaption of the micro-scale extraction and GC/FID or GC/MS, technique developed by Brophy et al. (1989). Six major groups of volatile (steam distillable) compounds (monoterpenes, sesquiterpene hydrocarbons, oxygenated sesquiterpenes [excluding eudesmols], eudesmols, triketones, and nor-triketones) and 3 groups of non-volatile or semi-volatile compounds (flavonoids, grandiflorone and nor-grandiflorone) were recognized in the leaf oil components. The active manuka honeys do not appear to be derived uniquely, or predominantly, from a single leaf oil chemotype.
255

Etude des mécanismes de pyrolyse en présence d'hydroxyde de tetramethylammonium de composés protéiques modèles. Implication pour la détection de matériel azoté dans la matière organique naturelle et l'identification de macromolécules sources

Gallois, Nicolas 13 May 2008 (has links) (PDF)
Malgré son implication importante dans de nombreux processus environnementaux, la matière organique naturelle (MON) reste mal caractérisée, principalement à cause du caractère réfractaire des structures dans lesquelles elle est impliquée. Si des fonctions amides ont été mises en évidence dans la MON, la structure moléculaire des unités associées est encore inconnue. La pyrolyse couplée à la chromatographie gazeuse et à la spectrométrie de masse (Py-GC-MS) en présence de Tetra-Methyl-Ammonium Hydroxyde (TMAH) est a priori un outil pertinent pour l'analyse de ces structures. Pour mieux comprendre le comportement des structures azotées de la MON au cours de la Py-GC-MS/TMAH, nous avons étudié par cette méthode, les 20 acides aminés protéiques, 17 dipeptides, 4 polypeptides et une protéine, la Sérum Albumine Bovine (SAB). Cette étude a permis de mettre en évidence les principaux mécanismes de pyrolyse des acides aminés (méthylation directe, cyclisation, dimérisation, homolyse, décarboxylation, et déamination), et l'influence de la liaison peptidique sur ces mécanismes. La Py-GC-MS/TMAH des dipeptides et des polypeptides a montré l'importance des produits de cyclisation, en particulier des diketopiperazines et de structures plus complexes basées sur 3 acides aminés, et des produits d'homolyse pour les acides aminés aromatiques. De plus, cette étude a permis d'établir une base de données des produits de pyrolyse des acides aminés et des 17 dipeptides. Enfin, la pyrolyse de la SAB en mélange avec les deux principales macromolécules présentes dans la biomasse (lignine et cellulose) montre que les coefficients de réponse sont défavorables à la protéine.
256

Effet de l'exercice sur les concentrations d'androgènes chez la jeune femme<br />Analyse de traces dans les urines<br />Mise au point d'une phase d'extraction à base d'empreinte moléculaire

Bayle, Marie-Laure 17 December 2008 (has links) (PDF)
La consommation frauduleuse de nandrolone est détectée dans les urines par la présence de ses métabolites isomères norandrostérone et norétiocholanolone. Afin de contrôler si, chez la femme, une activité sportive peut être responsable de l'augmentation de leurs productions endogènes, ainsi que de celles de la déhydroépiandrostérone et de l'androstérone, une méthode d'analyse urinaire faisant intervenir trois extractions sur phase solide suivies d'une analyse par GC-MS a été mise au point. Une correction des concentrations brutes en analytes a été appliquée par rapport au taux de créatinine, marqueur de la dilution des urines. Le traitement statistique des résultats obtenu à partir de 400 urines n'a montré aucun effet de l'exercice sur les concentrations en métabolites de la nandrolone, mais un effet modéré de l'exercice aérobie sur les concentrations en androstérone. Le statut hormonal des individus (phase du cycle menstruel et prise de contraceptif) a également été évalué. <br />Une amélioration de l'extraction a été ensuite proposée par la synthèse d'une phase stationnaire polymérique à impression moléculaire (MIP). Le MIP a été synthétisé dans des conditions favorisant la mise en place d'interactions non covalentes avec l'androstérone, ces mêmes interactions étant ensuite mises à contribution dans la rétention de la norandrostérone et de ses isomères lors de la percolation d'un échantillon sur la phase d'extraction. Conduisant à des résultats prometteurs, la technique semble intéressante en vue de l'analyse de traces de métabolites de la nandrolone grâce à une amélioration de la sélectivité de la méthode globale d'analyse
257

Identifiering av lakbara potentiellt farliga ämnen i gummiasfalt / Identification of leachable potential harmful substances in rubber asphalt

Gustavsson, Jakob January 2010 (has links)
<p>The main purpose of the project was to identify potential environmentally harmful substances which can be leached from rubber asphalt. A method for analysing asphalt was developed and three rubber asphalt materials were analysed after being cryogrinded. One of the materials was also tested in a road machine made for testing of asphalt paving. The particles created in the machine were analysed in the same manner as the cryogrinded asphalt materials.</p><p>The asphalt materials were leached by water during 24 hours. The leachates were extracted with dichloromethane, dried with sodium sulphate and concentrated to a small volume. The extracts were analysed with gas chromatography-mass spectrometry (GC-MS). Due to low concentrations of substances the GC-MS was operated in SIM-mode (Selected Ion Monitoring). Thirteen substances were chosen for the analysis. The substances were aniline, benzothiazole, butyl benzyl phthalate, bisphenol-A, decanoic acid, dibutyl phthalate, diethylhexyl phthalat, phenanthrene, chrysene, naphthalene, 4-n-nonyl phenol and 4-tert-octyl phenol. Benzothiazole and 4-tert-octyl phenol were detected and quantified in the leachates.</p><p>In addition to the analysis of organic substances, pH was measured too. The leachates produced in this project were also sent to an analysis company for several analyses, for example analysis of metals and sulphur. Toxicity tests were performed on the same leachates within an exam work made by Gro Runeman at Lund University. The results of the metal analysis, sulphur analysis, and toxicity tests are not covered within the scope of this report. For the results of these tests and analyses, see Gro Runeman’s report: <em>Evaluating toxicity of asphalt leachates</em>.</p> / <p>Detta examensarbete är utfört vid Statens Geotekniska Institut (SGI). Huvudsyftet med arbetet är att identifiera potentiellt miljöfarliga ämnen som kan laka ut från gummiasfalt. En metod för analys av asfalt har tagits fram och tre olika gummiasfalter har analyserats efter att ha kryomalts. En av dessa asfalter har också använts i en provvägmaskin där det damm som bildades har samlats upp och analyserats. Inom ramen för examensarbetet har också en litteraturstudie gjorts för att bland annat ta reda på vad som är gjort inom området sedan tidigare.</p><p>För att ta reda på vad asfalten innehåller för föreningar gjordes först en fastfasextraktion av krossad (ej kryomald) asfalt där diklormetan användes som lösningsmedel. Från början var tanken att en GC/MS-screening skulle göras för att på så sätt få en överblick av samtliga organiska ämnen som finns i asfalten men på grund av de väldigt låga halterna av i gaskromatografen analyserbara föreningar var det nödvändigt att begränsa analysen till några få föreningar. De föreningar som analysen inriktade sig mot var anilin, bensotiazol, bensylbutylftalat, bisfenol-A, dekansyra, dibutylftalat, di(etylhexyl)ftalat, fenantren, krysen, naftalen, 4-n-nonylfenol, pentaklortiofenol och 4-tert-oktylfenol.</p><p>Laktester utfördes genom att de kryomalda asfaltmaterialen lakades med vatten under 24 timmar. Efter extraktion, torkning och koncentrering analyserades lakextrakten med avseende på de föreningar som hittats vid fastfasextraktionen. I lakvattnen hittades bensotiazol samt 4-tert-oktylfenol. Dessa föreningar kvantifierades genom att en enpunktskalibrering gjordes.</p><p>Utöver analyserna ovan mättes även pH på lakvattnen. Lakvattnen skickades också på metall- och svavelanalys samt turbiditets- och fenolindexmätning till ett större analysföretag. Toxicitetstester har utförts på samma lakvatten av Gro Runeman inom ramen för ett examensarbete vid Lunds Universitet. För resultaten från toxicitetstester, metallanalyser samt turbiditets- och fenolindexmätningar hänvisas till Gro Runemans rapport: <em>Evaluating toxicity of asphalt leachates</em>. Delar av denna rapport är skrivna i samarbete med Gro Runeman.</p>
258

Purification, Stereoisomeric Analysis and Quantification of Biologically Active Compounds in Extracts from Pine Sawflies, African Butterflies and Orchid Bees

Bång, Joakim January 2011 (has links)
Stereochemistry plays an important role in nature because biologically important molecules such as amino acids, nucleotides and sugars, only exist in enantiomerically pure forms. Semiochemicals carry messages, between the same species (pheromones) and between different species (allelochemicals). Both pheromones and allelochemicals can be used as environmentally friendly pest management. Many semiochemicals, i.e. behaviour modifying chemicals, consist of pure or well-defined mixtures of stereoisomers, where some of the other stereoisomers can be repellent. It is therefore important to be able to separate them to produce a synthetic pheromone in a mixture that is attractive. Pine sawflies are a family of insects that in some cases can be severe defoliators of conifer trees. Diprion pini, Diprion similis and Neodiprion sertifer are severe pests for these trees and have got the most attention in pine sawfly pheromone studies. The pheromone precursors are stored in the female body as long-chain secondary alcohols, which, when released, are esterified to acetates or propionates. The alcohols are chiral, and normally one of the stereoisomer is the main pheromone component, sometimes possible together with other stereoisomers as essential minor components. Bicyclus is a genus of African butterflies, and especially Bicyclus anynana has become a popular model for the study of life history evolution, morphology, mating choice and genetics. The wing pattern of Bicyclus differs depending on the season, with large eyespots during the rain-season and small or absent spots during the dry season.  Euglossa is one of the genera among the orchid bees in the Neotropics that does not produce its own pheromone. Instead, the males collect fragrances from orchids and other sources and store them in a pocket in their hind legs. Both Bicyclus and Euglossa use semiochemicals similar to pine sawflies, and thus can be analysed by the same methods. Pheromones and other semiochemicals in insects are often present in low amounts in a complex matrix, and purification of the sample before chemical analysis is often required. A common method is gradient elution on a solid phase silica column. Separation of stereoisomers can be achieved either by using a column with a chiral stationary phase (CSP) or with pre-column derivatisation using a column with an achiral stationary phase (ASP) or a combination of both, with mass detection as the dominant detection method. The purpose of this work has been to improve the purification method, find suitable methods to separate the stereoisomers of secondary alcohols, and to apply this on extracts of insects. By selecting the right fractions to collect during gradient elution the purification method was optimised. To reduce plasticizer contamination from ordinary columns, solid phase columns of Teflon or glass were used. For pre-column derivatisation of different chiral alcohols various acid chlorides were tested. For the pine sawfly pheromone precursors enantiopure (2S)-2-acetoxypropionyl chloride was the best choice. To separate some of the stereoisomers achiral 2-naphthoyl chloride was used. For derivatisation of 6,10,14-trimethylpentadecan-2-ol (R)-trans-chrysanthemoyl chloride was the best choice. The derivatised alcohols were separated on different columns, both chiral and non-chiral. Varian FactorFour VF-23ms was chosen as a general-purpose column, the Agilent HP-88 column was the best column with an ASP of those tested, and the Chiraldex B-PA column (CSP) was the only one that could separate all eight stereoisomers of derivatised 3,7-dimethylundecan-2-ol, 3,7-dimethyldodecan-2-ol, and 3,7-dimethyltridecan-2-ol. To determine the stereoisomeric purity of standard solutions used in field experiments and extracts of different species of insects the optimised methods were applied. For extracts from B. anynana, Euglossa and Neodiprion lecontei this work describe the first determination of the stereochemistry of some of their semiochemicals. For the determination of the stereochemistry of chiral semiochemicals the methods for purification and separation presented herein have shown to be of great value. The results will hopefully contribute to a better understanding of the communication among insects, and ultimately to a more environmentally friendly pest control. / Många naturligt förekommande kemiska ämnen finns som två spegelbilder av varandra, ungefär som höger och vänster hand. Dessa kan ha helt olika egenskaper och det är därför viktigt att kunna separera dem. Insekter och andra djur använder olika doftämnen för att kommunicera med varandra, om det är inom samma art kallas de för feromoner. De kan bestå av ett ämne eller en blandning av flera. Dessa doftämnen kan man även använda för att på ett miljövänligt sätt bekämpa skadeinsekter. En fälla med syntetiskt feromon för en viss insekt lockar endast till sig den arten, medan alla andra är opåverkade. Eftersom dessa ämnen ofta finns som spegelbilder där kanske bara den ena är aktiv och den andra rent av frånstötande, måste man kunna separera dem för att framställa ett syntetiskt feromon som är attraktivt. Målet med detta arbete har varit att bestämma feromonet hos olika arter av tallsteklar som kan vara svåra skadedjur på tallskog. De metoder som tagits fram har även tillämpats på några arter av afrikanska fjärilar samt orkidébin från Centralamerika eftersom de använder snarlika doftämnen. Att få fram feromonet från en insekt är lite som att leta efter in nål i en höstack eftersom de ofta bara innehåller några miljarddels gram per individ. Provet behöver först renas, och en del av arbetet i det här projektet har gått ut på att ta fram en lämplig reningsmetod. Huvudfokus har dock varit på att ta fram metoder som kan separera och identifiera det eller de ämnen, och spegelbilder av dessa, som doftämnena består av. När lämpliga metoder tagits fram har extrakt av olika insektsarter analyserats. I några fall är det första gången som deras feromon bestämts i detalj. Resultaten kan förhoppningsvis bidra till en ökad kunskap om insekters sätt att kommunicera, och i slutändan till miljövänligare bekämpning av skadeinsekter.
259

Analytical techniques for quality assessment of separated and commingled recycled polymer fractions

Camacho, Walker January 2002 (has links)
Different methods for quality assessment of separated andcommingled plastics from household and electronic waste havebeen developed. Especial attention has been given tospectroscopic methods since they are non-destructive andrequire little or no sample preparation at all. A wide variety of low molecular weight compounds have beenidentified in recycled polyethylene (HDPE) and polypropylenefrom hard packaging waste by gas chromatography- massspectroscopy (GC-MS) after microwave assisted extraction (MAE).Low molecular weight substances such as alcohols, esters,ketones and fragrance and flavour compounds were detected inthe recycled resins. The major category of compounds identifiedin the virgin resins is conformed by aliphatic hydrocarbonssuch as alkanes and alkenes. It was found that theconcentration of aromatic hydrocarbons without functionalgroups, e.g. ethylbenzene and xylenes in recycled HDPE wasapprox. 5 times higher and equal to 120 and 35 ppb,respectively. The potential of near infrared (NIR) and Fourier transformRaman (FT-Raman) spectroscopy in combination with multivariateanalysis as a rapid, non-destructive and accurate analyticalmethod has been studied and the feasibility of these methodsfor at/in line characterisation of several properties ofrecyclates has also been explored. NIR in diffuse reflectance mode has been successfully usedfor quantification of antioxidants in polyethylene, thestandard error of prediction is almost comparable to the errorof wet methods, i.e., extraction plus liquid chromatography.The error of prediction of this method is 35 ppm for Irganox1010 and 68 ppm for Irgafos 168. The inaccuracy in thequantification of Irgafos 168 is due to the fact that thisantioxidant degrades during polymer processing. NIR and Mid-infrared (Mid-IR) worked well for fastdetermination of molecular weight and crystallinity of therecycled HDPE and acceptable errors of prediction, comparableto that of the reference methods, i.e. size exclusionchromatography (SEC) and differential scanning calorimetry(DSC) have been obtained. The present thesis also shows that NIR and Raman are goodcandidates for in/on line compositional analysis of mixedpolymer fractions from recycled plastic waste. Diffusereflectance NIR allows a rapid and reliable measurement ofpellets and requires no previous sample preparation. Thecomposition of binary blends can be determined with highaccuracy. The PP content in the PP/HDPE blends was predictedwith a RMSEP equal to 0.46 %w in the 0-15 %wt region and theRMSEP for PP in the PP/ABS blends was 0.3 %wt. The thermal and thermoxidative stability of recycled PP,HDPE and a 20/80 PP/HDPE blend subjected to multiple extrusionhave been studied by DSC, thermal analysis (TGA) andchemiluminiscence (CL). A decrease in Toxand OIT was observed after each extrusion step.The drop in OIT was sharper after the first two extrusions. TheOIT values produced by DSC and CL were in good agreement.However, CL provided more information about the oxidationprocess taking place in the blends. The moisture content in recycled polyamide 6,6 was readilydetermined by NIR in transmission mode and it could bepredicted with a RMSEP = 0.05 %wt. The accuracy of the methodappeared to be as good as that of the more time consumingthermal methods such as TGA, DSC and loss on dry (LOD), whichwere used as reference methods. The influence of differentamounts of water on the viscoelastic properties of nylon hasbeen investigated. <b>Keywords:</b>Recycling, HDPE, PP, blends, nylon 6,6, ABS,water content, MAE, GC-MS, NIR, FT-Raman, chemiluminiscence,low molecular weight compounds, antioxidant content,crystallinity, molecular weight, thermal stability,characterisation methods, analysis of polymers, blends.
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Methodological aspects of unspecific building related symptoms research

Glas, Bo January 2010 (has links)
This thesis deals with methological issues in the study of chemical exposure and sick building syndrome (SBS). SBS is a combination of general, mucosal and skin symptoms that some people experience when staying in specific buildings. The aim was to find chemical patterns associated with SBS, but also to address methological problems in such study. The plan was to conduct a case-control study comparing the two groups’ chemical exposure, where cases were defined as those having at least one general, one mucosal and one skin symptom each week the last three months. For the planning it was necessary to know if cases and controls could be selected from the same building. If everyone in a building have the same chemical exposure it is no use to compare exposure between two persons at the same workplace. In the first paper exposure to more than 100 compounds is compared between 79 participants working in eight buildings. It was found that for the majority of compounds the variation in exposure was larger within buildings than between buildings, which means that cases and controls could be allowed to work in the same building. The second paper is a comparison of three adsorbents usability in finding differences in chemical exposure between SBS cases and controls. This was done by using chemometrical methods but comparisons of sampled amounts, blank values and reproducibility were also done. Tenax TA was found to be the best adsorbent, hence used in the case-control study. In recent years ozone and ozone reaction products with unsaturated volatile organic compounds (VOCs) has been in focus. Nitrogen dioxide is another gas affecting oxidation of reactive VOCs. Formaldehyde is an irritant formed when unsaturated VOCs are oxidised, and in some studies a relation with SBS has been found. In paper three the relation between personal exposure to formaldehyde, nitrogen dioxide, ozone, terpenes and SBS has been investigated among more than 200 office workers in a case control study in Umeå and Vasa. Cases (based on symptoms during the week of measurements) had lower ozone exposure than controls. No further associations were found at present exposure levels. A planed analysis of relations to VOCs could not be done due to analytical problems, and problems due to difficulties with consistent identification of compounds in a very large data set. These problems are further discussed in the thesis. In the case-control, study participants answered questionnaires about symptoms during "the past three months", "right now" (when answering the questionnaire), and during the week of exposure measurements. In the fourth paper the stability of symptoms were compared by answers at different occasions. It was found that the case/control concept was as stable as individual symptoms. More participants with atopic disease and those 41 years old or younger changed class compared with those without atopic disease and older participants. Measurement activities appeared to make participants report more symptoms. Fatigue, dry eyes and dry skin are suggested to be symptoms with strongest, and illness/dizziness to be weakest association with IAQ. / KLUCK-projektet

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