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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.
31

New Calibration Approaches in Solid Phase Microextraction for On-Site Analysis

Chen, Yong January 2004 (has links)
Calibration methods for quantitative on-site sampling using solid phase microextraction (SPME) were developed based on diffusion mass transfer theory. This was investigated using adsorptive polydimethylsiloxane/divinylbenzene (PDMS/DVB) and Carboxen/polydimethylsiloxane (CAR/PDMS) SPME fiber coatings with volatile aromatic hydrocarbons (BTEX: benzene, toluene, ethylbenzene, and o-xylene) as test analytes. Parameters that affected the extraction process (sampling time, analyte concentration, water velocity, and temperature) were investigated. Very short sampling times (10-300 s) and sorbents with a strong affinity and large capacity were used to ensure a 'zero sink' effect calibrate process. It was found that mass uptake of analyte changed linearly with concentration. Increase of water velocity increased mass uptake, though the increase is not linear. Temperature did not affect mass uptake significantly under typical field sampling conditions. To further describe rapid SPME analysis of aqueous samples, a new model translated from heat transfer to a circular cylinder in cross flow was used. An empirical correlation to this model was used to predict the mass transfer coefficient. Findings indicated that the predicted mass uptake compared well with experimental mass uptake. The new model also predicted rapid air sampling accurately. To further integrate the sampling and analysis processes, especially for on-site or <i>in-vivo</i> investigations where the composition of the sample matrix is very complicated and/or agitation of the sample matrix is variable or unknown, a new approach for calibration was developed. This involved the loading internal standards onto the extraction fiber prior to the extraction step. During sampling, the standard partially desorbs into the sample matrix and the rate at which this process occurs, was for calibration. The kinetics of the absorption/desorption was investigated, and the isotropy of the two processes was demonstrated, thus validating this approach for calibration. A modified SPME device was used as a passive sampler to determine the time-weighted average (TWA) concentration of volatile organic compounds (VOCs) in air. The sampler collects the VOCs by the mechanism of molecular diffusion and sorption on to a coated fiber as collection medium. This process was shown to be described by Fick's first law of diffusion, whereby the amount of analyte accumulated over time enable measurement of the TWA concentration to which the sampler was exposed. TWA passive sampling with a SPME device was shown to be almost independent of face velocity, and to be more tolerant of high and low analyte concentrations and long and short sampling times, because of the ease with which the diffusional path length could be changed. Environmental conditions (temperature, pressure, relative humidity, and ozone) had little or no effect on sampling rate. When the SPME device was tested in the field and the results compared with those from National Institute of Occupational Health and Safety (NIOSH) method 1501 good agreement was obtained. To facilitate the use of SPME for field sampling, a new field sampler was designed and tested. The sampler was versatile and user-friendly. The SPME fiber can be positioned precisely inside the needle for TWA sampling, or exposed completely outside the needle for rapid sampling. The needle is protected within a shield at all times hereby eliminating the risk of operator injury and fiber damage. A replaceable Teflon cap is used to seal the needle to preserve sample integrity. Factors that affect the preservation of sample integrity (sorbent efficiency, temperature, and sealing materials) were studied. The use of a highly efficient sorbent is recommended as the first choice for the preservation of sample integrity. Teflon was a good material for sealing the fiber needle, had little memory effect, and could be used repeatedly. To address adsorption of high boiling point compounds on fiber needles, several kinds of deactivated needles were evaluated. RSC-2 blue fiber needles were the more effective. A preliminary field sampling investigation demonstrated the validity of the new SPME device for field applications.
32

New Calibration Approaches in Solid Phase Microextraction for On-Site Analysis

Chen, Yong January 2004 (has links)
Calibration methods for quantitative on-site sampling using solid phase microextraction (SPME) were developed based on diffusion mass transfer theory. This was investigated using adsorptive polydimethylsiloxane/divinylbenzene (PDMS/DVB) and Carboxen/polydimethylsiloxane (CAR/PDMS) SPME fiber coatings with volatile aromatic hydrocarbons (BTEX: benzene, toluene, ethylbenzene, and o-xylene) as test analytes. Parameters that affected the extraction process (sampling time, analyte concentration, water velocity, and temperature) were investigated. Very short sampling times (10-300 s) and sorbents with a strong affinity and large capacity were used to ensure a 'zero sink' effect calibrate process. It was found that mass uptake of analyte changed linearly with concentration. Increase of water velocity increased mass uptake, though the increase is not linear. Temperature did not affect mass uptake significantly under typical field sampling conditions. To further describe rapid SPME analysis of aqueous samples, a new model translated from heat transfer to a circular cylinder in cross flow was used. An empirical correlation to this model was used to predict the mass transfer coefficient. Findings indicated that the predicted mass uptake compared well with experimental mass uptake. The new model also predicted rapid air sampling accurately. To further integrate the sampling and analysis processes, especially for on-site or <i>in-vivo</i> investigations where the composition of the sample matrix is very complicated and/or agitation of the sample matrix is variable or unknown, a new approach for calibration was developed. This involved the loading internal standards onto the extraction fiber prior to the extraction step. During sampling, the standard partially desorbs into the sample matrix and the rate at which this process occurs, was for calibration. The kinetics of the absorption/desorption was investigated, and the isotropy of the two processes was demonstrated, thus validating this approach for calibration. A modified SPME device was used as a passive sampler to determine the time-weighted average (TWA) concentration of volatile organic compounds (VOCs) in air. The sampler collects the VOCs by the mechanism of molecular diffusion and sorption on to a coated fiber as collection medium. This process was shown to be described by Fick's first law of diffusion, whereby the amount of analyte accumulated over time enable measurement of the TWA concentration to which the sampler was exposed. TWA passive sampling with a SPME device was shown to be almost independent of face velocity, and to be more tolerant of high and low analyte concentrations and long and short sampling times, because of the ease with which the diffusional path length could be changed. Environmental conditions (temperature, pressure, relative humidity, and ozone) had little or no effect on sampling rate. When the SPME device was tested in the field and the results compared with those from National Institute of Occupational Health and Safety (NIOSH) method 1501 good agreement was obtained. To facilitate the use of SPME for field sampling, a new field sampler was designed and tested. The sampler was versatile and user-friendly. The SPME fiber can be positioned precisely inside the needle for TWA sampling, or exposed completely outside the needle for rapid sampling. The needle is protected within a shield at all times hereby eliminating the risk of operator injury and fiber damage. A replaceable Teflon cap is used to seal the needle to preserve sample integrity. Factors that affect the preservation of sample integrity (sorbent efficiency, temperature, and sealing materials) were studied. The use of a highly efficient sorbent is recommended as the first choice for the preservation of sample integrity. Teflon was a good material for sealing the fiber needle, had little memory effect, and could be used repeatedly. To address adsorption of high boiling point compounds on fiber needles, several kinds of deactivated needles were evaluated. RSC-2 blue fiber needles were the more effective. A preliminary field sampling investigation demonstrated the validity of the new SPME device for field applications.
33

O passado no presente: vestígios pré-coloniais como suporte analítico da paisagem no Vale do Soturno, RS / The past in the present: precolonial traces anda analytical support of the landscape in the Soturno river valley in the state of Rio Grande do Sul.

Juliana Rossato Santi 02 February 2010 (has links)
Este trabalho refere-se ao estabelecimento de populações humanas em tempos pretéritos e aos processos de interação que podem se desenvolver entre elas, visualisados pela arqueologia. Buscamos desvendar como ocorreu a ocupação humana (anterior a colonização) no Vale do Rio Soturno, região central do estado do Rio Grande do Sul, Brasil. Os sítios arqueológicos estudados espalhados por esta micro-região foram: Várzea dos Bugres; Cerro dos Bugres; Cerro do Tope; Moacir Rossato, com remanescentes culturais atribuídos aos Guarani. Tentamos entender quais as escolhas que estes grupos fizeram em relação aos recursos ambientais locais, suas estratégias de exploração, as relações entre si e as escolhas na elaboração de seus utensílios remanescentes de uso cotidiano. Percebemos que os grupos atuantes neste espaço optaram por adotar algumas características técnicas específicas, mas no geral seguem o padrão clássico de ocupação Guarani. Realizamos ainda um trabalho com a comunidade que vive no local atualmente, utilizando a metodologia da educação patrimonial, a fim de que esse patrimônio cultural estudado se tornasse conhecido e aceito junto àqueles que serão seus guardiões. Apesar de não contarmos com um número de sítios relevante para um estudo de caráter regional, acreditamos ter contribuído para a arqueologia Guarani apresentando especificidades culturais de grupos que ocuparam um local que até então não fora estudado. / This search refers to the establishment of human populations in past times and the interaction process that can develop between them, shown by archaeology. We seek to discover how human occupation occurred (before colonization) in Sortuno river valley, in central Rio Grande do Sul, Brazil. The archaeological sites studied in this micro-region were: Várzea dos Bugres; Cerro dos Bugres; Cerro do Tope; Moacir Rossato, with the remaining cultures attributed mostly to the Guarani. We try to understand what choices these groups have in relation to local environmental resources, their exploration strategies, relations between themselves and the choices in the development of their remaining fixtures of everyday use. We realize that groups working in this area have chosen to adopt some specific technical features, but in general follow the classic pattern Guarani occupation. We also worked with the community that lives on site using the heritage education methodology, so that the cultural heritage studied could become known and accepted between those who will be their guardians. Although we could not count with a certain number of sites that study regional character, we believe to have contributed it to archaeological Guarani, showing specific cultural groups that occupied a place that until then had not been studied.
34

9 actions - Sensoric Measures for Eternal Efficiency

Olsson, Linn January 2021 (has links)
9 actions - Sensoric measures for eternal efficiency is a project negotiating with the consequences of modernist urban planning and its infrastructure which has produced phenomenons like “non-places”, places which neither become or are used according to the procedure of care that our public spaces require. Situated within this idea, I establish a methodology which is formulated as an eternal site analysis, which showcases the process as total and in constant transition, a perspective that rather than becoming an dogma aims to question the raised methodology in relation to site and the analysis within the field of interior architecture. The methodologies aim to embody the sequence of time and space, to bodily engage our senses and re-evaluate the relation to the surrounding environment. This is captured in 9 actions inspired by methods within performance, architecture and installation art. The sequence is examined with different mediums, such as filmmaking, drawings, 3d scans, diagrams, sound recordings, photographs and various other interpretations. A compilation of these acts emphasizes the importance of the methodology of the process and its ability to reconfigure. Concluded and executed at Konstfacks Spring exhibition 2021, visitors were invited to interact with a selection of actions examined during the project. Described below, 3 of the exhibited sequences: “REPET Workshop”; as an act of instruction to understand and question the bodily configuration of normative behaviours in relation to sites. “Pedestrian Measures”; a documented act where the participant was dressed in a reflective apparatus in order to experience irregularities hidden in the spatial hierarchy of sites - as fields of perceived space. “Den gemensamma kroppen”; A collective act, pronounced as the common body of the space. An installation where visitors were invited to dress and interact bodily to engage full focus. A reflective action configuring the use of the body and its sensory abilities in context of common spatial production.
35

Förtätningsprojekt i Umeå : Gestaltning av Stadsliden 2:3 på sluttande mark / Densification project in Umeå : Formation of Stadsliden 2:3 on sloping ground

Lindmark Starkenberg, Frida, Nilsson, Lisa January 2014 (has links)
Umeå är en växande stad som ligger längs norrlandskusten. Kommunen har starka mål och ambitioner för att staden ska växa de närmaste 25 åren. Kommunen planerar att komplettera ett område vid namn Berghem med 80-100 lägenheter. Ett helt nytt kvarter ska bildas på nuvarande naturmark i sluttande terräng. Kvarteret ligger nära Umeå centrum och bara ett stenkast ifrån Berghems eget centrum. Berghem är en av de dyraste stadsdelarna i Umeå att köpa en bostad på och kötiderna är bland de längsta för hyresrätter. Vid byggnation på denna plats behöver många faktorer beaktas. Att anpassa byggnaden efter platsen och dess terräng har varit arbetets stora utmaning och fokus har lagts på förstudiearbetet med en ingående platsanalys över planområdet och dess omgivning. Förstudiearbetet och platsanalysen består bland annat av resonemang kring hur solen påverkar byggnadernas placering, hur omkringliggande byggnader påverkar exploateringsgraden och hur markens terräng inverkar på utformningen. Detta arbete har som syfte att gestalta ett förslag för det nya kvarteret. Visionen har varit att skapa ett kvarter med stark anknytning till omkringliggande natur. / Umeå is a growing city that lies along the coast of Norrland. The municipality has strong goals and ambitions for the city to grow over the next 25 years. The municipality plans to complete an area named Berghem with 80-100 apartments. A new block shall be formed on current natural land on sloping ground. The area is near Umeå city center and just a stone throw away from Berghem’s own center. Berghem is one of the most expensive neighborhoods in Umeå to buy an apartment and queues for rental apartments are among the longest. Building on this area needs a lot of factors to take into account. To adapt the buildings to the area and its terrain has been the works greatest challenge, focus has been placed on the pilot study with a detailed site analysis of the area and its surroundings. Pilot study and site analysis consists among others on reasoning about how the sun affects the placement of the buildings, how the surrounding buildings affects on the rate of exploitation and how soil terrain affecting the composition. This work aims to design concept drawings for the new area. The vision was been to create a neighborhood with strong ties to the surrounding nature.
36

State Formation in the Cretan Bronze Age

TenWolde, Christopher Andrew January 2008 (has links)
No description available.
37

Den Kulturella Padelhallen : En studie på implementeringen av kulturella verksamheter i padelhallar / The Cultural Padelhall : A study on the implementation of cultural activites in padelhalls

Jonasson, Christoffer, Alkelid, Olle January 2024 (has links)
I det här kandidatarbetet undersöks padelhallar för att hitta potentiella gestaltningslösningar för de utmaningar verksamheterna står inför idag. Vid en statistikundersökning ser man tydligt att antalet utövare har sjunkit kraftigt och att flera hallar runt om i Sverige har behövts stänga igen. Syftet med arbetet är att undersöka huruvida potentiella kulturella verksamheter kan kombineras med dessa hallar för att få ner kostnaderna och skapa ett gynnsamt samarbete. I detta arbete presenteras en analysprocess och en anpassad gestaltningsprocess som visar på hur dessa potentiella kulturella verksamheter både kan identifieras samt implementeras i padelhallar. Genom att undersöka teorier såsom “Low Road and High Road”, “Junkspace” och “The Duck and the Decorated Shed” har arbetet fått en klarare blick över vad padelhallar är, samt vad man behöver tänka på vid en anpassad gestaltning. En detaljerad platsanalys har även gjorts på ett urval padelhallar för att jämföra vilka urbana kontexter de kan befinna sig i, vilka olika konstruktioner de kan ha, vilka planlösningar osv. Utöver detta har även detaljplaner analyserats. Under projektets gång har en av hallarna, lokaliserad i Västra Hamnen, Malmö, hamnat hos en konkursförvaltare, vilket bestämde valet av vilken hall gestaltningen skulle ta form vid. Den slutliga gestaltningen visar på ett konceptuellt förslag över hur lokala kulturella verksamheter kan kombineras med denna hall. / In this thesis, padelhalls are investigated in order to find potential design solutions for the challenges businesses are facing today. A statistical survey clearly shows that the number of practitioners has fallen sharply and that several halls across Sweden have had to close. The purpose of this work is to investigate whether potential cultural activities can be combined with these halls in order to reduce costs and create a favourable collaboration. This work presents an analysis process and an adapted design process that shows how these potential cultural activities can both be identified and implemented in padelhalls. By examining theories such as “Low Road and High Road”, “Junkspace” and “The Duck and the Decorated Shed”, the work has gained a clearer view of what padelhalls are and what needs to be considered when creating an adapted design. A detailed site analysis has also been done on a selection of padelhalls to compare which urban contexts they can be in, which different constructions they can have, which layouts, etc. In addition to this detailed plans have also been analysed. During the course of the project, one of the halls, located in Västra Hamnen, Malmö, ended up with a bankruptcy trustee, which determined the choice of which hall the design would take form at. The final design shows a conceptual proposal for how local cultural activities can be combined with this hall.
38

Habitat Selection in Four Sympatric Small Mammal Species and the Effects of Potential Predators on Peromyscus Leucopus

Chupp, Adam Daniel 01 January 2005 (has links)
I examined the effects of potential predators in relation to habitat selection in Peromyscus leucopus. I also examined habitat selection in three other sympatric species (Blarina brevicauda, Blarina carolinensis, Sorex longirostris). I utilized data fiom 49 sampling sites on National Park Service land; Petersburg National Battlefield Eastern Front Unit (15), Five-Forks Unit (17), Appomattox Court House National Historical Park (15) and Booker T. Washington National Monument (12). Sites were categorized by location (park unit) and habitat type (i.e. bottom-land hardwood), and the microhabitat within each sampling site was characterized by four variables (% cover of grasses, herbs, shrubs, and volume of downed wood). Importance values of tree species within each sampling site were also measured. Peromyscus leucopus, B. brevicauda, B. carolinensis, and S. longirostris were captured in all habitat types. Low capture rates for shrew species and high variability in the abundance of shrew species among all sampling sites were likely responsible for the lack of differences in abundance among habitats (p > 0.05). Peromyscus leucopus represented 76% of the captures among prey species and was the only species to demonstrate differences in relative abundance among habitat types. The relative abundance of P. leucopus was higher in bottom-land hardwood habitat when compared to pine forest plantation habitat (ANOVA, p P. leucopus among these habitat types may be explained by differences in understory structural diversity. Furthermore, the corresponding increase in the relative abundance of Procyon lotor (the most abundant predator during the study) in structurally heterogeneous habitat (bottom-land hardwood) suggests the importance of anti-predator behaviors within these habitat types. Ultimately, this may suggest that prey cannot escape the presence or calculate the abundance of predators and instead simply avoid dangerous habitats. Although the relative abundance of the most abundant predator (P. lotor) and prey (P. leucopus) species were positively associated within certain habitat types, a negative association between predator and prey species abundance was evident within parks. In the Eastern Front unit the relative abundance of prey (P. leucopus, S. longirostris) was lower in comparison to the Five-Forks unit while the abundance of P. lotor was higher (ANOVA, p P. lotor, Didelphis virginiana, and Urocyon cinereoargenteus were higher in the Eastern Front unit when compared to the Five-Forks unit. It appeared that the lethal effects of predators are evident at larger scales (within parks) despite the anti-predator behaviors of prey at smaller scales (within microhabitats). My results indicate that at larger scales (within parks) the lethal effects (removal of prey) of abundant predators may overwhelm the non-lethal effects (anti-predator behavior) exhibited by prey at smaller scales, especially in areas where structurally heterogenous habitats are lacking.
39

A variabilidade espacial no sítio Osvaldo : estudo de um assentamento da Tradição Barrancóide na Amazônia Central / Spatial variability in the Osvaldo site : study of a settlement of the Barrancoid Tradition in Central Amazonia

Portocarrero, Ricardo Andres Chirinos 11 April 2007 (has links)
O presente trabalho é uma tentativa de desenvolvimento de novas metodologias para o entendimento do uso do espaço interno em sítios arqueológicos de terra firme da Amazônia Central. Há décadas diversos investigadores vêm debatendo sobre a variabilidade destes assentamentos (Meggers, Lathrap, Myers, Roosevelt, Heckenberger e Neves, entre outros). Nosso caso de estudo é o sítio Osvaldo, localizado na área de interfúvio dos rios Negro e Solimões, na margem sul do Lago do Limão. Este sítio apresenta internamente áreas heterogêneas, com variabilidade de profundidade de terra preta antropogênica de densidade de fragmentos cerâmicos, estes afiliados culturalmente à Tradição Barrancóide/fase Manacapuru e à fase Paredão. A análise de agrupamento espacial e padrão composicional mostram similitudes e diferenças entre as áreas mencionadas, evidenciando uma complexidade social interna, cujo entendimento, a partir de analogias etnográficas, tem relevância não apenas para a problemática intra-sítio, mas também para a discussão sobre as relações entre sítios a nível regional e sobre os movimentos migratórios de populações pré-coloniais. / The present work is an attempt to develop new methodologies for the understanding of the use of the internal space in archeological hinterland (terra firme) sites in Central Amazon. For decades, several investigators have debated the variability of these settlements (Meggers, Latrhap, Myers, Roosevelt, Heckenberger and Neves, among others). Our case study is the Osvaldo site, located between Solimões and Negro rivers at the South margin of Limão lake. This site internally displays heterogeneous areas with different depths of anthropogenic terra preta and variable density of pottery fragments culturally linked to the Barrancoid Tradition / Manacapuru phase and Paredão phase. The spatial clustering analysis and the composítional pattern show similarities and differences among the mentioned areas, presenting internal social complexity, of which the observation, from ethnographical analogies, is relevant not only for the intra-site problematic but also for the discussion on the relations among sites at regional level and for understanding the migratory movements of pre-columbian populations.
40

Desenvolvimento de metodologias eletroanalíticas para a determinação de metais em biocombustíveis empregando a análise por injeção em batelada (BIA) / Development of electroanalytical procedures for determination of metals in biofuels employing batch injection analysis (BIA)

Tormin, Thiago Faria 20 December 2016 (has links)
CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / FAPEMIG - Fundação de Amparo a Pesquisa do Estado de Minas Gerais / Nesta tese foi demonstrado que a associação da técnica eletroanalítica Voltametria de Redissolução Anódica de Onda Quadrada (SWASV, do inglês, Square-Wave Anodic Stripping Voltammetry) com a Análise por Injeção em Batelada (BIA, do inglês, Batch- Injection Analysis) permite o desenvolvimento de métodos analíticos para a determinação de metais (Cu, Cd, Pb, Hg e Zn) em amostras de etanol combustível e biodiesel. Metais podem ser incorporados aos biocombustíveis em processos de armazenagem e transporte, podendo causar danos irreversíveis ao biocombustível, o qual pode danificar motores e causar problemas ambientais. Logo, justifica-se o presente trabalho pela necessidade do desenvolvimento de métodos analíticos visando o controle de qualidade em relação ao teor de metais nestas amostras, preferencialmente métodos de fácil manuseio, rápidos, de baixo custo e robustos. BIA-SWASV permitiu a determinação direta (sem qualquer diluição da amostra) de Cd, Pb, Cu e Zn em etanol combustível empregando eletrodos de Au e filme de Hg. Limites de detecção na faixa de 0,6 a 5 pg L-1, faixa linear de 12,5 a 200 pg L-1 e valores de recuperação entre 87 e 109% foram obtidos para análises de 1 mL de amostra e tempo de deposição de 90 s (tempo total de cada medida de ~200 s). O tempo de injeção da amostra pela micropipeta eletrônica usada no sistema BIA foi de 40 s, ou seja, a deposição dos metais ocorreu mesmo após o término da injeção (transporte difusional das espécies ao eletrodo). Além disso, esta tese apresenta a associação de eletrodos impressos (SPE, do inglês, Screen-Printed Electrode) ao sistema BIA visando o desenvolvimento de métodos analíticos com características portáteis. Este sistema foi combinado a outros componentes que funcionam com uso de baterias como, pipetas eletrônicas, mini-potenciostatos e computador laptop, e aplicado à determinação de metais (Pb, Cu e Hg) em amostras de biodiesel após digestão ácida. Empregaram-se nos experimentos SPE’s com tinta condutora de Au (SPGE, do inglês, Screen-Printed Gold Electrode) como eletrodo de trabalho, reduzindo o volume de amostra a 200 pL (em eletrodos convencionais utilizou-se 1000 pL) com tempo de injeção de 40 s (velocidade de injeção de 5 gL s-1) e, nestas condições, obtiveram-se limites de detecção abaixo de 1,0 gg L-1 (equivalente a 6 gg g-1), faixa linear entre 20 e 280 gg L-1 e valores de recuperação entre 90 e 110% para amostras de biodiesel fortificadas. O baixo consumo de amostra no sistema BIA prolongou o tempo de vida útil do SPGE para um dia inteiro de análises (210 injeções). O sistema BIA associado a técnicas eletroanalíticas permitiu o desenvolvimento de métodos analíticos de baixo custo, simples, precisos, que empregam pequeno volume de amostra, portáteis (sobretudo com o emprego de SPE’s), que podem ser aplicados para a determinação de rotina e em campo de metais em amostras de etanol combustível e biodiesel. / In this thesis it is shown that the association of electroanalytical technique Square- Wave Anodic Stripping Voltammetry (SWASV) with Batch-Injection Analysis (BIA) allows the development of analytical methods for determination of metals (Cu, Cd, Pb, Hg and Zn) in ethanol fuel and biodiesel samples. Metals can be incorporated into biofuels during storage and transportation processes, which can damage engines and cause environmental problems. Therefore, it becomes necessary to develop analytical methods aiming the quality control of metals in these samples, preferably methods that are easy to operate, fast, inexpensive and robust. BIA-SWASV allowed direct determination (no dilution of the sample) of Cd, Pb, Cu and Zn in fuel ethanol employing Au and Hg film electrodes. Detection limits in the range of 0.6 to 5 pg L"1, linear range from 12.5 to 200 pg L-1 and recovery values of between 87 and 109% were obtained for analysis of 1 mL of sample and deposition time of 90 s (total time of each measurement of ~200 s). The time of sample injection by the electronic micropipette used by the BIA system was 40 s, that is, the deposition of metal occurred even after the end of injection (diffusional transport of species to the electrode). In addition, in this thesis it is presented the combination of Screen-Printed Electrodes (SPE) to the BIA system aimed to the development of analytical methods with portable characteristics. This system was combined with other components that operate using batteries as electronic pipettes, mini- potentiostat and laptop computer, and applied to the determination of metals (Pb, Cu and Hg) in biodiesel samples after acid digestion. It was used in the experiments SPE's with Au conductive ink as a working electrode (SPGE), reduced the volume of sample to 200 pL (in conventional electrodes was used 1000 pL) with injection time of 40 s (injection rate of 5 pL s-1), and in these conditions, detection limits lower than 1,0 pg L-1 (equivalent to 6 pg g-1), linear range between 20 and 280 pg L-1 and recovery values between 90 and 110% for biodiesel fortified samples were obtained. The low sample consumption extended the lifetime SPGE’s for a whole day of analysis (210 injections). BIA system associated with electroanalytical techniques allowed the development of inexpensive,simple, accurate, portable (especially with the use of SPE's) analytical methods, employing reduced sample volume, which can be applied for the routine and on-site determinations of metals in ethanol fuel and biodiesel samples. / Tese (Doutorado)

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