Neste projeto foram abordados procedimentos analíticos para extração, separação e identificação de espécies de arsênio encontradas normalmente em quantidades de traços e ultra-traços em amostras biológicas e ambientais. Entre as amostras alvo deste estudo, teve-se alimentos de origem marinha como por exemplo camarão. Foi avaliada a estabilidade das espécies de arsênio nas soluções geradas pelos processos de extração. Para separação das espécies inorgânicas (arsenito e arsenato), metiladas (ácidos mono e dimetil arsênio) e orgânicas (arsenobetaina) empregaram-se as técnicas eletroforese capilar (CE) e cromatografia líquida (LC). Os sistemas de separação para a determinação das espécies de arsênio foram acoplados com os espectrômetros massas (ICP-MS), e de fluorescência atômica (AFS). Os sistemas acoplados apresentaram resolução e sensibilidade na determinação das espécies de arsênio nas amostras estudadas neste trabalho. A extração com água de espécies de As utilizando-se banho de ultra-som apresentou eficiência acima de 78%. A estabilidade das espécies nas soluções padrão e nos extratos das amostras foi mantida por um período de até uma semana quando armazenadas em geladeira (+4°C). Visando uma política de química limpa, foi desenvolvida uma metodologia para evitar desperdiço preparando micro-volumes de amostras e soluções padrão, para especiação de arsênio por eletroforese capilar. Para tal se empregou um injetor seqüencial, também foi desenvolvido um dispositivo de injeção hidrodinâmica para eletroforese capilar. Além disto, as soluções residuais geradas durante a pesquisa analítica foram tratadas para a recuperação de arsênio e boro. A extração no ponto nuvem foi empregada para recuperar As entanto que a precipitação por mineralização hidrotérmica foi aplicada para a recuperação de B . A aplicação deste procedimento resultou na extração de 80% de arsênio e 75% de boro. Isto, permitiu converter grandes volumes de resíduos líquidos perigosos em um pequeno volume de resíduos sólidos / Analytical procedures for extraction, separation and identification of arsenic species at ultra-trace levels in biological and environmental samples were investigated. Stability studies of arsenic species in sample extracts and standard solutions were carried out. Separation of arsenite, arsenate, monomethylarsonic and dimethylarsinic acids and also arsenobetaine were carried out by capillary electrophoresis or liquid chromatography. Determination of the separated arsenic species was accomplished by coupling the separation techniques to inductively coupled plasma mass spectrometry (ICP-MS) or atomic fluorescence spectrometry (AFS). Satisfactory resolution and sensibility were achieved by the coupled systems described. Extraction efficiency better than78% were achieved with water in an ultrasonic bath at the laboratory temperature (23-27°C). Whereas, stability of species in solutions stored in refrigerator at +4°C was efficient for aperiod up to one week. Micro-volumes of standards and sample solutions mixed in a sequential injector were prepared for arsenic speciation by capillary electrophoresis, aiming green chemistry. A time controlled micro-volume injector device for hydrodinamic injections was also developed. Finally, waste solutions from arsenic speciation analysis in a system with hydride generation were treated for arsenic and boron removal. Cloud point extraction for recovery of arsenic and hydrothermal mineralization of boron by calcium hydroxide were employed. Satisfactory removal of 80% of arsenic and 75% of boron from waste solution was achieved. These procedures allowed to reduce volumes of hazardous waste solutions

Neste projeto foram abordados procedimentos analíticos para extração, separação e identificação de espécies de arsênio encontradas normalmente em quantidades de traços e ultra-traços em amostras biológicas e ambientais. Entre as amostras alvo deste estudo, teve-se alimentos de origem marinha como por exemplo camarão. Foi avaliada a estabilidade das espécies de arsênio nas soluções geradas pelos processos de extração. Para separação das espécies inorgânicas (arsenito e arsenato), metiladas (ácidos mono e dimetil arsênio) e orgânicas (arsenobetaina) empregaram-se as técnicas eletroforese capilar (CE) e cromatografia líquida (LC). Os sistemas de separação para a determinação das espécies de arsênio foram acoplados com os espectrômetros massas (ICP-MS), e de fluorescência atômica (AFS). Os sistemas acoplados apresentaram resolução e sensibilidade na determinação das espécies de arsênio nas amostras estudadas neste trabalho. A extração com água de espécies de As utilizando-se banho de ultra-som apresentou eficiência acima de 78%. A estabilidade das espécies nas soluções padrão e nos extratos das amostras foi mantida por um período de até uma semana quando armazenadas em geladeira (+4°C). Visando uma política de química limpa, foi desenvolvida uma metodologia para evitar desperdiço preparando micro-volumes de amostras e soluções padrão, para especiação de arsênio por eletroforese capilar. Para tal se empregou um injetor seqüencial, também foi desenvolvido um dispositivo de injeção hidrodinâmica para eletroforese capilar. Além disto, as soluções residuais geradas durante a pesquisa analítica foram tratadas para a recuperação de arsênio e boro. A extração no ponto nuvem foi empregada para recuperar As entanto que a precipitação por mineralização hidrotérmica foi aplicada para a recuperação de B . A aplicação deste procedimento resultou na extração de 80% de arsênio e 75% de boro. Isto, permitiu converter grandes volumes de resíduos líquidos perigosos em um pequeno volume de resíduos sólidos / Analytical procedures for extraction, separation and identification of arsenic species at ultra-trace levels in biological and environmental samples were investigated. Stability studies of arsenic species in sample extracts and standard solutions were carried out. Separation of arsenite, arsenate, monomethylarsonic and dimethylarsinic acids and also arsenobetaine were carried out by capillary electrophoresis or liquid chromatography. Determination of the separated arsenic species was accomplished by coupling the separation techniques to inductively coupled plasma mass spectrometry (ICP-MS) or atomic fluorescence spectrometry (AFS). Satisfactory resolution and sensibility were achieved by the coupled systems described. Extraction efficiency better than78% were achieved with water in an ultrasonic bath at the laboratory temperature (23-27°C). Whereas, stability of species in solutions stored in refrigerator at +4°C was efficient for aperiod up to one week. Micro-volumes of standards and sample solutions mixed in a sequential injector were prepared for arsenic speciation by capillary electrophoresis, aiming green chemistry. A time controlled micro-volume injector device for hydrodinamic injections was also developed. Finally, waste solutions from arsenic speciation analysis in a system with hydride generation were treated for arsenic and boron removal. Cloud point extraction for recovery of arsenic and hydrothermal mineralization of boron by calcium hydroxide were employed. Satisfactory removal of 80% of arsenic and 75% of boron from waste solution was achieved. These procedures allowed to reduce volumes of hazardous waste solutions

Spatially-resolved measurements of flame temperature have been demonstrated with diode lasers for the first time. The technique is based on the use of blue diode lasers to perform laser-induced fluorescence on indium atoms seeded to the flame. Temperature measurements have been carried out in laminar flames both by the two-line atomic fluorescence technique, and also by a novel line-shape thermometry method that requires the use of only a single diode laser. The first part of this work involved the development of blue extended cavity diode lasers with favourable tuning properties. Two custom-designed extended cavity diode lasers (ECDL) have been built, emitting at wavelengths of around 410 nm and 451 nm respectively. These devices are capable of mode-hop free tuning over ranges greater than 90 GHz. The performance of these devices exceeds that of commercially available systems and a patent application has been filed. High resolution fluorescence spectroscopy has been performed on both the 52P1/2→62S1/2 and 52P3/2→62S1/2 transitions of indium atoms seeded at trace quantities into atmospheric pressure flames. In both cases, the spectra obtained show excellent agreement with a theoretical fit based on the individual hyperfine components of the transition. The two ECDLs have been used to build a sensor for the measurement of temperature in combustion systems. It is much simpler, more compact, less expensive, and more versatile than any previously existing device. The two lasers were used sequentially to probe indium atoms seeded to the flame. The ratio of the resulting fluorescence signals is related to the relative populations in the two sub-levels of the spin-orbit split ground state of indium, and thus to the temperature. Temperature measurements have been successfully performed in a laminar flame and the data thus obtained do not need to be corrected by any ‘calibration constant’. This novel thermometry technique offers a robust alternative to traditional methods involving bulky high power lasers. A further development has been made by demonstrating a fluorescence line-shape thermometry technique requiring only a single diode laser excitation source. Progress has been made towards the goal of rapid temperature measurements appropriate to the study of turbulent flames. This involved the development of a simple technique for actively locking the wavelength of the blue diode laser to a resonance line of the tellurium molecule. A high-speed thermometry system would work by rapidly switching between the two locked laser beams using an optical modulator.

The diploma thesis is dealing with monitoring of arsenic in foodstuffs. The aim of this thesis is the determination of arsenic in samples of fish and rice and the study of forms, in which arsenic occurs, using speciation analysis. Arsenic is known as a toxic element, but its measure of toxicity depends on the chemical form it occurs in. Arsenic is present in the environment naturally or it gets in the environment by human activities. Complete characterization of arsenic compounds is necessary to understand intake, accumulation, transport, detoxification and activation of this element in the natural environment and living systems. The field of arsenic speciation analysis has grown rapidly in recent years, because determination of the total element content is not sufficient in the case of arsenic. Speciation method was done using separation by high performance liquid chromatography and detection by atomic fluorescence spectrometry with hydride generation. Extractable arsenic was present in the form of nontoxic arsenobetaine in all analysed samples of fish. In samples of rice there was confirmed the presence of toxic inorganic species of arsenic, esspecially As (III), but their concentration was at low level.

The aim of the theses was determination of selenium species in yeast Saccharomyces cerevisiae cultivated in medium with added inorganic form of selenium (Sodium Selenite). Concentrations of Sodium Selenite in cultivation medium were 0,1; 1; 10 and 100 mg.l-1. Cultivation was undertaken in fermenting tub for period of 72 hours. Cultivated yeasts were extracted by use of enzymes and subsequently the species of selenium in particular parts of yeasts were determined. In order to determine selenium species, the method of high-performance liquid chromatography in combination with atomic fluorescent spectrometer and technique of hydride generation was used. Having analysed different fractions of the yeasts Saccharomyces cerevisiae it was ascertained that during cultivation the sorption of selenium occurred in form of Se4+ in cell membranes while in cytoplasm no inorganic forms of selenium were found. Furthermore, it was stated that yeasts Saccharomyces cerevisiae are able to metabolically change inorganic forms of selenium to organic forms (selenomethionine), while these forms are present in cytoplasm and they are likely to be bound to proteinic structures of cell membranes. An increase of concentration of Se4+ in cell membranes could be observed as a result of increasing concentration of Sodium Selenite in cultivation medium. In proteinic structures the concentration of organic selenium forms increased only to concentration 10 mg.l-1 of Sodium Selenite in cultivation medium.

Rtuť je v přírodě přirozeně se vyskytujícím toxickým prvkem, jehož globální emise jsou ovlivňovány zejména antropogenními zdroji znečištění. Obrovský globální nárůst v usazování rtuti, zejména ve vodných ekosystémech, byl zaznamenán současně s počátkem průmyslové revoluce. Sedimenty jsou posledním místem úložiště nejrůznějších komplexů rtuti. Rtuť však zde může být přeměněna na toxičtější organickou formu, methylrtuť, pomocí transformačních procesů kontrolovaných různými fyzikálními, chemickými, ale i biologickými faktory. Navíc mohou být specie rtuti remobilizovány ze sedimentů pomocí difuze a resuspenzace a tak se sedimenty mohou stát i potenciálním zdrojem rtuti. Proces bioakumulace a bioobohacování tak pokračuje v potravním řetězci, ve kterém se člověk, i další zvířata, stává konzumentem methylrtuti. Stanovení celkové koncentrace rtuti není dostačující k porozumění osudu rtuti v přírodním prostředí a tak stanovení MeHg poskytuje nezbytnou doplňující informaci. Dostatečně citlivá a přesná analytická metoda pro stanovení specií rtuti je nezbytným nástrojem environmentální chemie. Metody vhodné pro stanovení specií rtuti v sedimentech jsou popsány v části metodologie disertační práce. Metoda stanovení methylrtuti v sedimentech pomocí automatické Headspace vybavené pastí („trap“) a spojené s plynovou chromatografií a fluorescenční detekcí je zde také popsána. Zvláštní pozornost je také věnována potřebám zásad čistého vzorkování, skladování vzorků a přípravě vzorků před samotou analýzou, jakož i samostatné části věnující se terénní studii rtuti a methylrtuti v sedimentech vytipovaných lokalit. Sedimenty jižní Moravy a severní Francie jsou srovnány z hlediska znečištění rtutí. Specie rtuti a další ukazatele (Fe, Mn, S) byly analyzovány v sedimentech, pórové vodě a povrchové vodě řek Dele a Lys (Francie) a Jihlava a Morava (Česká republika). Z hlediska posouzení vodních ekosystémů a jejich znečištění rtutí, je vhodné znát koncentraci rtuti v pórové vodě a posoudit dostupnost rtuti ze sedimentů. Technika difuzního gradientu v tenkém filmu je vhodným způsobem jak stanovit koncentraci rtuti v pórové vodě sedimentů. Do roku 2005 bylo použití této techniky pro měření rtuti značně limitováno. Ale nedávný pokrok především v dostupnosti možných sorpčních gelů vhodných pro stanovení rtuti umožnilo využití této techniky i pro stanovení rtuti. Byly použity různé sorpční gely: Spheron.Thiol, Duolite GT-73 a TiO2. Řeka Dele představuje past enormního množství antropogenní rtuti pocházející z průmyslových zdrojů a je považována za potenciální významný zdroj methylrtuti pro okolní prostředí a živé organismy především. Poslední část dizertační práce se zabývá aplikací dobře zavedeného experimentu využívajícím stabilní isotopy ke studiu metylačních a demethylačních procesů v sedimentech řeky Dele. Obohacené stabilní značkovače rtuti v anorganické formě (199Hg) and methylované formě (201MeHg) byly přidány do sedimentů. Tyto označené specie rtuti tak pomohly sledovat osud specií rtuti a vypočítat rozsah jejich přeměny v průběhu experimentu.

The presented thesis deals with UV-photochemical generation of volatile compounds of Se and Te from various species. The aim of the project was to expand the current state of knowledge by the application of photocatalytic reduction of higher oxidation states of Se and Te for the speciation analysis based on UV-photochemical generation of volatile compounds. The first step of the study was the assembly of the apparatus for the photocatalysed UV-photochemical generation of volatile compounds. The material of reactor and the whole experimental set-up were based on literature survey and previous research done in our research group. Experiments were directed towards finding the optimum conditions for generation of volatile compounds of selected model elements Se and Te. Se was studied as the element most commonly determined by the UV-photochemical generation of volatile compounds. Conversely, Te was selected as a model analyte representing elements forming less stable volatile compounds. The second part was the application of the optimised method of photocatalysed UV- photochemical generation of volatile Se compound to the determination of Se in water matrices, liquid certified reference materials and also samples of dietary supplements. TiO2/UV-photochemical generation was also successfully modified to...

This master's thesis deals with the optimization of conditions of chemical hydride generation (HG) of bismuth, its atomization and detection by atomic absorption spectrometry (AAS) and atomic fluorescence spectrometry (AFS). Two types of atomizers were used for atomization of volatile species, a miniature diffusion flame for AAS as well as for AFS and a flame-in-gas-shield atomizer for AFS. At first, the parameters of HG in a flow injection mode were optimized - the concentration of hydrochloric acid, the concentration of sodium borohydride and the volume of the reaction coil. Subsequently, the atomization conditions were optimized using both atomizers. The parameters optimized were hydrogen fraction, total gas flow rate and observation height. Due to the more complicated construction of the FIGS atomizer, more parameters were studied, such as the oxygen flow rate through the capillary and the flow rate of shielding argon required for shielding the free atoms. A special part of the thesis dealt with the optimization of the optical path of the atomic fluorescence spectrometer, the selection of an interference filter and the optimization of a power supply of an electrodeless discharge lamp. It was found that under optimum conditions of generation, atomization and detection excellent detection limits...

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146f. / Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2013-04-03T13:18:57Z No. of bitstreams: 1 Tese Hadla S Ferreira.pdf: 1335067 bytes, checksum: d1c32c23138aa8d7c8145b340260a496 (MD5) / Approved for entry into archive by Ana Hilda Fonseca(anahilda@ufba.br) on 2013-04-23T15:10:36Z (GMT) No. of bitstreams: 1 Tese Hadla S Ferreira.pdf: 1335067 bytes, checksum: d1c32c23138aa8d7c8145b340260a496 (MD5) / Made available in DSpace on 2013-04-23T15:10:36Z (GMT). No. of bitstreams: 1 Tese Hadla S Ferreira.pdf: 1335067 bytes, checksum: d1c32c23138aa8d7c8145b340260a496 (MD5) Previous issue date: 2009 / CAPES / Neste trabalho, foram desenvolvidos métodos para determinação de cádmio e chumbo em amostras ambientais e antimônio e arsênio em amostras de alimentos, utilizando técnicas de espectrometria atômica. A determinação do cádmio e do chumbo foi realizada através de um sistema de injeção em fluxo acoplado a técnica TS FF AAS. Os íons de cádmio (II) e chumbo (II) foram retidos em uma mini-coluna de Amberlite de XAD – 7 impregnada com ditizona. O planejamento Box- Behnken foi empregado para determinação das condições ótimas da etapa de concentração do chumbo e do cádmio. Os limites de detecção foram de 0,012 e 0,34 μg L-1 para cádmio e chumbo, respectivamente. O método foi aplicado em amostras de resíduos de refinaria de petróleo. A exatidão foi confirmada por análise da CRM NIST 1643d. Foi também desenvolvido um método para determinação de espécies tóxicas de arsênio e antimônio em amostras de alho e cogumelos, respectivamente por HG AFS. A determinação das espécies (III) e (V) de arsênio e antimônio foram baseadas na eficiência de geração de hidreto empregando NaBH4, com e sem uma prévia redução com KI, usando equações proporcionais correspondentes para as duas condições de medida. Os analitos foram extraídas com ácido sulfúrico nas condições de 1,0 e 0,5 mol L-1 para arsênio e antimônio, respectivamente. Com o método desenvolvido obteve-se limites de detecção de 0,6, 1,1, 0,84 e 1,4 ng g-1 para Sb(III), Sb(V), As(III) e As(V), respectivamente. A exatidão do método foi confirmada através de testes de adição e recuperação das espécies bem como, um material de referência certificado NIST 1573a. Um método para determinação de arsênio total em vinho também foi desenvolvido. O arsênio foi determinado por FI-HG AAS com um sistema de atomização eletrotérmica. O planejamento Box-Behnken foi utilizado na determinação das condições ótimas para geração de hidreto. Com método proposto obteve um limite de detecção de 0,06 μg L-1 e foi aplicado em 20 amostras de vinhos comercializadas do Brasil. / Salvador