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No. of bitstreams: 1 TeseEFB.pdf: 1317890 bytes, checksum: 82fae1c425af918f9fd0775d660bec52 (MD5) Previous issue date: 2015-10-22 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / In this work, it was developed a procedure for the determination of metals in cosmetics, employing the techniques ICP OES, GF AAS, LIBS and LA-ICP OES; in addition, it was explored the potential of chemometric tools. For the determination of Cd, Co, Cr, Cu and Ni by ICP OES and Pb by GF AAS in eyeshadow and lipstick samples, it was developed a sample preparation method using diluted nitric acid and a hot block. For the optimization of chemical parameters of sample preparation and operating parameters of ICP OES, it was used factorial design and for data analysis and selection of the best working conditions, the desirability functions were employed. In total, it was analyzed 30 samples of cosmetics (21 eyeshadow and 9 lipstick), of different colors, brands and from different countries (Brazil, USA and China). These samples were analyzed in triplicate and with standard addition to perform the recovery calculations. The analyzed samples showed concentration of Cd and Pb within the limits set by the laws, however, 7 eyeshadow samples had concentration of Cr and Ni above than 5 g g-1. In the case of lipstick samples, all values were below this safe limit. All samples analyzed by ICP OES and GF AAS were also analyzed without sample pretreatment by LIBS. The values obtained in the quantitative analysis were employed in the development of supervised classification models such as the KNN and SIMCA. For the obtainment of these models, data of children´s cosmetics samples were included. The classes considered in the models were: below and above the legislation, with a limit set at 5 mg kg-1, according to the recommendations in the literature. In addition to analysis of eyeshadow and lipstick samples, it was explored the potential of the techniques LIBS and LA-ICP OES along with chemometric tools for exploratory analysis of sunscreen samples. The results were obtained for three different equipment (two LIBS and one LA-ICP OES), and several models employing principal component analysis (PCA) were generated. The signals profile of Al, Ni, Ti, and Zn were analyzed and the results obtained between the three equipment were similar. / Nesta tese foram desenvolvidos procedimentos para a determinação de metais em cosméticos, empregando as técnicas ICP OES, GF AAS, LIBS e LA-ICP OES, além de explorar as potencialidades das ferramentas quimiométricas. Para a determinação de Cd, Co, Cr, Cu e Ni por ICP OES e Pb por GF AAS em amostras de sombra e batom, foi desenvolvido um método de preparo de amostra empregando ácido nítrico diluído e um bloco digestor. Para a otimização dos parâmetros químicos do preparo de amostra e dos parâmetros operacionais do ICP OES, utilizou-se planejamentos fatoriais e para o tratamento dos dados e seleção das melhores condições de trabalho, foram empregadas as funções de desejabilidades. No total, foram analisadas 30 amostras de cosméticos (21 amostras de sombra e 9 amostras de batom), de diferentes cores, marcas e provenientes de diferentes países (Brasil, EUA e China). Essas amostras foram analisadas em triplicata e com a adição de padrão para realização dos cálculos de recuperação. As amostras analisadas apresentaram concentrações de Cd e Pb dentro dos limites estabelecidos pelas legislações, entretanto, 7 amostras de sombra apresentaram concentrações de Cr e Ni superiores a 5 μg g-1. No caso das amostras de batom, todos os valores estavam abaixo desse limite seguro. As amostras analisadas por ICP OES e GF AAS também foram analisadas, sem o tratamento prévio das amostras, por LIBS. Os valores adquiridos nas análises quantitativas foram empregados no desenvolvimento de modelos de classificação supervisionados, como o KNN e o SIMCA. Para a construção desses modelos, foram incluídos os dados de amostras de cosméticos infantis. As classes consideradas nos modelos foram: acima e abaixo da legislação, com um limite estipulado em 5 mg kg-1, segundo as recomendações de trabalhos disponíveis na literatura. Além das análises das amostras de sombra e batom, foram exploradas as potencialidades das técnicas LIBS e LA-ICP OES em conjunto com as ferramentas quimiométricas, para análises exploratórias das amostras de protetor solar. Os resultados foram obtidos por três equipamentos diferentes (dois LIBS e um LA-ICP OES) e vários modelos empregando a análise de componentes principais (PCA) foram gerados. Os perfis dos sinais de Al, Ni, Ti e Zn foram analisados e os resultados obtidos para os três equipamentos foram semelhantes.

Elemental analysis can become an important piece of evidence to assist the solution of a case. The work presented in this dissertation aims to evaluate the evidential value of the elemental composition of three particular matrices: ink, paper and glass. In the first part of this study, the analytical performance of LIBS and LA-ICP-MS methods was evaluated for paper, writing inks and printing inks. A total of 350 ink specimens were examined including black and blue gel inks, ballpoint inks, inkjets and toners originating from several manufacturing sources and/or batches. The paper collection set consisted of over 200 paper specimens originating from 20 different paper sources produced by 10 different plants. Micro-homogeneity studies show smaller variation of elemental compositions within a single source (i.e., sheet, pen or cartridge) than the observed variation between different sources (i.e., brands, types, batches). Significant and detectable differences in the elemental profile of the inks and paper were observed between samples originating from different sources (discrimination of 87 – 100% of samples, depending on the sample set under investigation and the method applied). These results support the use of elemental analysis, using LA-ICP-MS and LIBS, for the examination of documents and provide additional discrimination to the currently used techniques in document examination. In the second part of this study, a direct comparison between four analytical methods (µ-XRF, solution-ICP-MS, LA-ICP-MS and LIBS) was conducted for glass analyses using interlaboratory studies. The data provided by 21 participants were used to assess the performance of the analytical methods in associating glass samples from the same source and differentiating different sources, as well as the use of different match criteria (confidence interval (±6s, ±5s, ±4s, ±3s, ±2s), modified confidence interval, t-test (sequential univariate, p=0.05 and p=0.01), t-test with Bonferroni correction (for multivariate comparisons), range overlap, and Hotelling’s T2 tests. Error rates (Type 1 and Type 2) are reported for the use of each of these match criteria and depend on the heterogeneity of the glass sources, the repeatability between analytical measurements, and the number of elements that were measured. The study provided recommendations for analytical performance-based parameters for µ-XRF and LA-ICP-MS as well as the best performing match criteria for both analytical techniques, which can be applied now by forensic glass examiners.

Aujourd’hui, le principal facteur limitant le photovoltaïque est le prix élevé du kWh produit par les modules PV. Pour faire face à cette difficulté, les recherches actuelles se concentrent autour de plusieurs leviers et solutions alternatives : la réduction du coût énergétique avec notamment la réduction du coût de la matière première, qui consiste en la diminution de l’épaisseur des wafers de silicium, ou encore l’élaboration de cellules en couches minces de silicium. Ce dernier procédé a pour but de s’affranchir de l’étape de sciage des blocs de silicium, nécessaire pour la réalisation de plaquette photovoltaïque de faible épaisseur. C’est cette dernière approche qui nous a conduits à proposer un procédé d’élaboration de couches minces à l’aide d’un plasma et du chauffage du substrat. Par ailleurs, quel que soit le procédé choisi pour atteindre la cristallinité et la pureté exigées pour le grade solaire, il est nécessaire de disposer de technique analytique multiélémentaire pour contrôler l’évolution de la pureté en fonction des paramètres. La LIBS que nous avons développée au laboratoire offre l’opportunité de répondre à ces attentes : très basses limites de détection tout en permettant un suivi en ligne du silicium à l’état solide ou en fusion. / Today, the main limiting factor of PV is the high price of electricity production by the PV modules. To cope with this difficulty, current researches focus on several ways and alternatives solutions: reducing energy costs including reducing the cost of the raw material, which consists in reducing the thickness of silicon wafers or in the development of cells in thin silicon layers. The latter process is intended to overcome the sawing step of silicon ingots which is necessary for the realization of photovoltaic wafer. It is this very approach that led us to develop a method to prepare thin films by using plasma and heating the substrate. Moreover, whatever the method chosen to achieve the required crystallinity and purity for solar grade, it is necessary to have a multi-elements analytical technique to control the evolution of purity. In our laboratory, we have developed LIBS which can meet these expectations, i-e very low detection limits while allowing online tracking of silicon in solid or liquid state.

Táto diplomová práca sa zaoberá klasifikáciou kovov pomocou spektroskopie laserom indukovanej plazmy (LIBS) a chemometrických metód. Práca poskytuje prehľad o štúdiách na danú tému. Sú vybrané tri široko používané chemometrické klasifikačné metódy: "Soft Independent Modeling of Class Analogy" (SIMCA), "Partial Least Squares Discriminant Analysis" (PLS-DA) a variácia umelých neurónových sietí (ANN), "Feedforward Multilayer Perceptron". Rôzne prístupy k prieskumovej analýze su tiež preskúmané. Metódy sú stručne opísané. Následne sú klasifikátory experimentálne porovnané.

The thesis deals with the possibilities of identifying the relevant tire traces at the place of a traffic accident based on their physical characteristics. Braking traces on the road are one of the most important objective elements for accident analysis, their easy and accurate detection is very important for accurate accident assessment. With the increasing technical equipment of vehicles, especially with the introduction of newer generations of braking assistance systems, traces left by the tires become almost invisible to the human eye. It is therefore highly desirable that their detection should be not only as accurate as possible but also as easy and fast as possible, not only for forensic experts, but especially for members of the traffic police departments. In line with the development and introduction of new safety and assistance systems for vehicles should also be the development of means and methods of providing the basis for technical analysis of traffic accidents. Reality shows that the procedures, even if still functional, are practically identical for several decades, are dependent on the subjective capabilities of the documenting person. An essential element of the work, compared to the previously described measurement procedures, is the use of modern methods and devices at the highest known level of knowledge. The aim is to find and verify a simple, accurate, subjectively least influenced detecting method for tire traces on the road. A series of measurements confirmed the possibility of using the thermal camera at the technical level usually available at the place of the accident, under limited atmospheric and time conditions. In addition, laser-induced plasma spectroscopy and rLIBS were used. This method of detecting spotless tire treads can be marked as a minimally feasible documentary and at the same time as fast enough, based on the measurements made and the intended removal of defects of the instrument in the development phase of the prototype.

The goal of this thesis is to design a scanning system for method of laser induced breakdown spectroscopy. The thesis contains research about laser induced breakdown spectroscopy, scanning system including all used components and chemical mapping of sample´s surface. In this thesis, the scanning system is combined with F-theta lens. The construction and optical design of the scanning system, evaluation of measured results and comparison with original motorized positioning is included.

This diploma thesis deals with the structural and optomechanical design of automatization of focusing laser beam for a remote laser spectroscopy device. The chosen solution uses an active rangefinder and a rotary unit to control the change of the focus plane of the device's optic system. The dependence of the focus plane’s change on the shift of lens in the focus plane was practically measured. For proper control of the rotary unit, this dependency is needed. Structural parts were made based on the created drawing documentation. The structural parts were mounted in the existing assembly of the device together with the purchased components. The proposed solution enables a change of the optical system, for example, in order to obtain a more appropriate range of focal planes.

This master's thesis deals with the design and implementation of universal user interface for detection devices used in Laser-induced breakdown spectroscopy. The design and implementation are based on analysis of current state of instrumentation used in laser spectroscopy. The user interface should be able to work with high repetition frequency of measurement. Acquired spectra should be visualised to user and it is also necessary to save this data on hard drive. The resulting application must be universal. It means the application must support various types and vendors of detection devices.

This diploma thesis describes optimization of the experimental parameters for Laser-induced breakdown spectroscopy of plant samples. First part deals with the theoretical method of LIBS and explains the principles and terms. In the next part there is described device which was used for measurements. Main part of diploma thesis describes creation of program for measurement-automation. Main task of program was to solve the connection of autofocus on the sample with the sample automatic movement. Furthermore are described and elaborated specific measurements for optimization of the experimental parameters for Laser-induced breakdown spectroscopy of plant samples.

This diploma thesis describes the design of a translation stage for focusing objective inside the LIBS interaction chamber. It contains a description of the fundamentals and basic functions of LIBS spectroscopy. Moreover, in the thesis an overview of different translation stages as possible LIBS components is given. Their advantages and disadvantages for use in a vacuum translation stage construction are evaluated. The thesis describes the final solution of a linear translation stage for focusing objective, and his advantages for LIBS method