Orientador: José Anchieta Gomes Neto / Banca: Pedro Vitoriano Oliveira / Banca: Marcia Andreia Mesquita Silva da Veiga / Resumo: Foi desenvolvido um método para a determinação espectrométrica de fósforo em insumos agroindustriais. O método está baseado na determinação por Espectrometria de Absorção atômica com Fonte Contínua de Alta Resolução (HR-CS AAS) utilizando a linha atômica 213,618 nm e bandas de 246,400 nm e 324,616 nm. Foram estudadas as melhores condições para a análise via absorção pelas bandas de PO e da linha de P atômica. Para a primeira, a melhor forma de análise foi utilizar a chama oxidante ar / acetileno, já para a última situação a atomização foi pela utilização de uma chama oxidante de acetileno / óxido nitroso. As melhores condições de funcionamento, tais como altura do queimador, fluxo de gases e taxa de aspiração da amostra foram definidas, sendo seus valores ideais para cada comprimento de onda respectivamente: 246,400 nm (9 mm - 0,186 - 5 mL min-1), para 324,616 nm (8 mm - 0,170 - 5 mL min-1) e de 213,618 nm (4 mm - 0,450 - 5 mL min-1). Boa linearidade foinobtida para o intervalo de concentração 250 - 4000 mg L-1 P usando o modo de integração do sinal de absorbância CP ± 2 (5 pixels), utilizando-se os sais Na2HPO3.5H2O, NaH2PO4, NH4H2PO4 e H3PO4. Os resultados mostraram que era irrelevante a natureza dos compostos para obter um padrão de P. Quatro diferentes modos de integração de absorbância foram avaliados: CP ± 1 (3 pixels), CP ± 2 (5 pixels), CP ± 3 (7 pixels) e CP ± 4 (9 pixels). Foi observado que a sensibilidade (inclinação da curva e massa característica) melhoraram com o aumento do número de pixels. O método de determinação de P pelo HR-CS FAAS em insumos agroindustriais foi comparada com a titulação. A exatidão e precisão foram de acordo com 95% de confiança, o desvio padrão relativo (RSD) obtido foi de 2,0%. Boas recuperações, cerca de 98%, foi obtida a partir de testes de adição e recuperação. / Abstract: It was developed a method for spectrometry determination of phosphorus in agroindustrial products. The method is based on the determination by high-resolution continuum source flame atomic absorption spectrometry technique (HR-CS FAAS) using the atomic line 213,618 nm and bands of 246,400 nm and 324,616 nm. It was studied the best conditions for the analysis, for the absorption by bands of PO and the line of P atomic. To the first the best form of analysis would be using an oxidizing air/acetylene flame for analyte atomization and the last an oxidizing acetylene/nitrous oxide flame. The best operating conditions was defined as the burner high, the gas flow rate and aspiration rate of the sample. The values for these operations conditions are respectively: to 246,400 nm ( 9 mm - 0,186 - 5 mL min-1), to 324,616 nm ( 8 mm - 0,170 - 5 mL min-1) and to 213,618 nm ( 4 mm - 0,450 - 5 mL min-1). Good linearity was obtained for the concentration range 250 - 4000 mg L-1 P using the wavelength integrate absorbance in CP ± 2 (5 pixels), using the salts Na2HPO3.5H2O, NaH2PO4, NH4H2PO4 e H3PO4. The results showed that the was irrelevant to the nature of the compound to obtain a standard of P. Four different wavelength integrated absorbance were evaluated: CP ± 1 (3 pixels), CP ± 2 (5 pixels), CP ± 3 (7 pixels) and CP ± 4 (9 pixels). It was observed that the sensitivity (slope and characteristic mass) improved with increased number of pixels. The method of analysis of P by HR-CS FAAS in agroindustrial products was compared with the titration. The accuracy and precision was agreement at 95% confidence level, the relative standard deviation (RSD) obtaneid was 2,0%. Good recoveries, about 98%, was obtained using test of addition and recovery. / Mestre

<p> Nanomaterials are the focus of intense research efforts in a variety of fields because of dramatic differences in properties when compared to the corresponding bulk materials. Catalysis is one material property that can become more pronounced at the nanoscale. By lowering energy requirements for chemical reactions, catalysts reduce production costs in diverse sectors of the economy, including medicine, transportation, environmental protection, oil and gas, food, and synthetic materials. Transition metals are an important class of catalysts capable of facilitating reduction and oxidation of molecular species. Since the discovery of transition metal catalysts nearly 200 years ago, certain metals were considered more active as catalysts (i.e., Pt, Pd, and Ru), while others (Au) appeared to have negligible catalytic activity as bulk materials. In recent years, gold nanoparticles (AuNPs) have become a fast-growing field of research owing to their unexpected catalytic properties not present in the bulk material. However, unsupported AuNPs are highly prone to flocculation and subsequent reduced catalytic activity. The choice of an appropriate aggregation-resistant stabilizing ligand for these nanoparticles is an important part of maintaining nanoscale catalytic properties. Additional stability is provided by anchoring AuNPs to support materials, allowing for dramatic improvements in catalyst lifetimes. This work discusses the development of novel diamond support materials for improving the stability of catalytically active AuNPs. Synthetic nanodiamond is a widely available, inexpensive, and robust material that has found applications in a wide range of commercial abrasives, lubricants, and composite materials. By exploiting the rich surface chemistry of nanodiamond, we have developed versatile catalyst support materials that offer unrivaled chemical and mechanical stability. Various nanodiamond surface modifications are readily prepared using a combination of chemical vapor deposition, photo-active polymer chemistry, and synthetic organic chemistry techniques. Control over the surface chemistry and properties of the resulting nanodiamond allow for increased stability of AuNPs via surface anchored thiol and amine moieties. The use of diamond as a support material should allow a wide variety of noble and nonprecious metal composite materials to be used as catalysts in harsh chemical environments not suitable for existing support materials.</p><p>

<p> The events on September 11^th 2001 and subsequent attacks in America and around the world have brought a renewed interest in the nation&rsquo;s security including the concern over the use of a nuclear or a radiological dispersal device (RDD). Research utilizing NAA and ICP-MS has been done in two separate projects in order to help address some of these concerns. A research assistantship from Savannah River National Laboratory was granted in order to identify the impurities and isotope ratios of ¹⁹²Ir sources (chapters 2-4). An electrochemical dissolution method of the iridium was developed and used for sample preparation for ICP-MS analysis. ICP-MS analysis was then used to identify and quantify impurities and isotope ratios in iridium from various sources. The second research project has developed a series of lanthanide phosphate based nanoparticles for use as tagging and tracking agents (chapters 5-7). The composition of the nanoparticles were varied to provide a unique signature that can be rapidly and precisely measured in the field via neutron activation analysis. The nanoparticles could be used as a real-time in the field method for tracking and identifying materials such as explosives in a post detonation scenario.</p><p>

<p> The use of spectrofluorometers to examine nanomaterials is quite popular using either fluorescence or synchronous measurements. However, understanding how a material&rsquo;s optical properties can influence spectral acquisition are of great importance to accurately characterize nanomaterials. This dissertation presents a series of computational and experimental studies aimed at enhancing the quantitative understanding of nanoparticle interactions with matter and photons. This allows for more reliable spectrofluorometer based acquisition of nanoparticle containing solutions. </p><p> Chapter I presents a background overview of the works described in this dissertation. Correction of the gold nanoparticle (AuNP) inner filter effect (IFE) on fluorophore fluorescence using PEGylated AuNPs as an external reference method is demonstrated in Chapter II. The AuNP IFE is corrected to quantify tryptophan fluorescence for surface adsorbed proteins. We demonstrate that protein adsorption onto AuNPs will only induce ~ 20% tryptophan fluorescence reduction instead of the commonly assumed 100% reduction. </p><p> Using water Raman intensities to determine the effective path lengths of a spectrofluorometer for correction of fluorophore fluorescence is discussed in Chapter III. Using Ni(NO3)2 and K2Cr2O7 as Raman IFE references, the excitation and emission path lengths are found to exhibit chromophore and fluorophore independence, however path lengths are spectrofluorometer dependent. </p><p> Finally, ratiometric resonance synchronous spectroscopy (R2S2) is discussed in Chapter IV. Using a combination of UV-vis and R2S2 spectroscopy, the optical cross sections of a wide range of nanomaterials were determined. Also on-resonance fluorescence in solution is demonstrated for the first time. The nanoparticles discussed range from photon absorbers, scatterers, simultaneous photon absorbers and scatterers, all the way to simultaneous photon absorbers, scatterers, and emitters.</p>

Doutoramento em Química Analítica / PhD Degree - Analytical Chemistry / Nesta dissertação descrevem-se vários sistemas de fluxo, desenvolvidos com o objectivo de permitirem efectuar em linha alguns tipos de pré-tratamento da amostra muito comuns na análise laboratorial, visando contribuir para facilitar a aplicação e expandir as potencialidades analíticas da espectrofotometria atómica e da espectrometria de massa em análise elementar, em Química Clínica. No Capítulo de Introdução a esta dissertação é feita uma descrição sumária do interesse da análise elementar inorgânica no contexto da Química Clínica e descrevem-se as estratégias de fluxo e as técnicas instrumentais mais comummente utilizadas para esse fim, com especial destaque para a descrição dos conceitos e princípios básicos da técnica de ICP-MS. No trabalho experimental descrito nos primeiros três primeiros Capítulos foram utilizadas técnicas de espectrofotometria atómica e foram empregues diferentes estratégias de fluxo, nomeadamente multicomutação e multi-impulsão. Concretamente, construíram-se sistemas capazes de adequarem, em linha, a concentração do analito ao intervalo de resposta instrumental linear, quer por meio de procedimentos de diluição, quer por meio de procedimentos de pré-concentração. No primeiro trabalho descrito envolvendo multi-impulsão, são apresentados ainda os resultados obtidos no estudo da influência exercida por um fluxo pulsado, característico daquele tipo de sistemas, sobre os processos de aspiração e nebulização das soluções próprios do equipamento de espectrofotometria atómica. No trabalho apresentado no último Capítulo descreve-se um sistema de SIA que permite a separação/pré-concentração dos analitos, neste caso PGEs, a partir de amostras de urina, de modo a serem posteriormente quantificados por ICP-MS, com um analisador de massas do tipo quadrupolo. / In this dissertation several flow systems are described, which were developed in order to allow performing on line some sample pretreatments that are very common in laboratory analysis. These flow systems were intended to allow an easier application and expansion of the analytical potentialities of atomic spectrophotometry and mass spectrometry in elemental analysis, in Clinical Chemistry. In the Chapter of Introduction to this dissertation a brief description of the interest of the inorganic elemental analysis in Clinical Chemistry context is made, and flow strategies and the instrumental techniques more commonly used for that purpose are described, giving special emphasis to the description of the concepts and basic principles of ICP-MS technique. In the experimental work described in the first three Chapters, atomic spectrophotometric techniques were used and different flow strategies were employed, namely multicommutation and multipumping. Concretely, flow systems capable of adjusting, on line, the concentration of the analyte to the instrumental linear range, either by means of dilution procedures or by means of preconcentration procedures, were assembled. In the first work described involving multipumping, the results obtained in the study on the influence exerted by a pulsed flow, which is a feature of that type of systems, in the process of solutions aspiration and nebulization that are characteristic of atomic spectrophotometry equipment, are also presented. In the work presented in the last Chapter, a SIA flow system that allows the separation/preconcentration of the analytes, which in this case are PGEs, from urine samples, in order to allow their subsequent quantification by ICP-MS with quadrupole mass analyzer, is described.

Doutoramento em Ciências Farmacêuticas / PhD in Pharmaceutical Sciences

Doutoramento em Ciências Farmacêuticas / PhD in Pharmaceutical Sciences

Doutoramento em Ciências Farmacêuticas / PhD in Pharmaceutical Sciences

Doutoramento em Ciências Farmacêuticas / PhD in Pharmaceutical Sciences

Doutoramento em Química Analítica / PhD Degree - Analytical Chemistry