<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

Doutoramento em Química Analítica / PhD Degree - Analytical Chemistry

Doutoramento em Ciências Farmacêuticas / PhD in Pharmaceutical Sciences