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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.
141

Stanovení mikro a makro prvků v balených vodách technikou ICP-OES / Determination of micro and macro elements in bottled water by ICP-OES technique

Herman, Vít January 2015 (has links)
This Master’s thesis deals with the determination of selected micro and macro elements in bottled water purchased in retail chains Czech Republic. There are described macro elements and micro elements that occur in the waters, bottled waters legislation and the most frequent used instrumental methods for elemental analysis. In this work for the analysis of bottled water were used methods optical emission spectrometry with inductively coupled plasma (ICP-OES) and ion chromatography (IC). Elemental composition of bottled water after analysis corresponded to the composition indicated on the labels, there were recorded only minor deviations from the reported concentrations. All bottled water meets the conditions of the legislation of the Czech Republic. The measured data were statistically processed in the XL Stat program and by multivariate data analysis was examined whether it is possible to individual bottled water from each other based on the analyzes differentiate, which can help in verifying the authenticity of bottled water and in the detection of adulteration of bottled water for profit.
142

Stanovení nutričních vlastností mleté papriky různého geografického původu / Determination of the nutritional properties of paprika of different geographic origin

Kovaříková, Tereza January 2017 (has links)
This master thesis deals with the analysis of nutritional properties of paprika condiment with different geographic origin. The theoretical part contains botanical description of red pepper (Capsicum annuum L.), its chemical composition, process of production of paprika and then they are described analytical methods suitable for determination of fundamental nutrional properties. Experimental part is focused on the preparation of samples and their analysis. In total, 11 samples were selected for the experiment, 5 of them had a protected designation of origin. These samples were from Slovakia, Hungary, Bulgary, Romania, Turkey and Spain. The Soxhlet extraction was used for the analysis of the fat content, Kjeldahl method was used to determine gross protein. High-performance liquid chromatography (HPLC) was chosen to determine carbohydrates and capsaicin. Induction-coupled plasma emission spectroscopy (ICP-OES) was used for elemental analysis. The results were compared with each other and with available databases and literature. For comparing and finding certain connections, the principal component analysis (PCA) was selected.
143

Development and optimization of methods for elemental quantitative analysis of catalysts and polymers through laser ablation-ICP techniques

Villaseñor Milán, Ángela 25 July 2018 (has links)
En la presente Tesis Doctoral la técnica de ablación laser acoplada a ICP-OES/MS ha sido empleada para analizar muestras sólidas, como catalizadores usados en el refinado del petróleo y polímeros. Se han llevado a cabo dos tipos de análisis, un análisis global de las muestras que proporciona información general y un análisis localizado que permite obtener información acerca de la distribución espacial de los elementos de interés en las muestras. Las diferentes variables de la técnica ablación láser son estudiadas con el fin de seleccionar aquellas que conducen una señal alta y estable, así como a un menor grado de fraccionamiento. Este estudio se realiza para cada tipo de muestra, ya que los resultados dependen de la matriz estudiada. Además, en esta Tesis doctoral se desarrolla un método de calibración para llevar a cabo un análisis cuantitativo de las muestras sólidas, basado en la deposición de patrones líquidos sobre la muestra sólida. Este método es conocido como “dried droplet calibration approach” (DDCA), y permite cuantificar elementos presentes en muestras sólidas sin necesidad de usar materiales de referencia sólidos. Este nuevo método de calibración compensa el fraccionamiento elemental y los efectos de matriz, proporcionando resultados exactos y preciosos para muestras complejas tales como vidrios, catalizadores y polímeros.
144

Uso del nebulizador ultrasónico con el espectrómetro de emisión óptica por plasma inducido (ICP OES) para mejorar los límites de detección en la cuantificación de metales en muestras de aguas y aguas residuales.

Lagos Orovilla, Mario Robertho January 2016 (has links)
En los últimos años, las nuevas legislaciones nacionales e internacionales, establecen nuevos límites de detección para la cuantificación de metales a niveles traza, en muestras de suelos, aguas y aguas residuales. Por otro lado, la literatura científica y los fabricantes de instrumentos analíticos muestran aplicaciones de mejora en los límites de detección del Espectrómetro de emisión óptica por plasma acoplado inductivamente (ICP OES) al utilizar un nebulizador ultrasónico. Esta mejora se debe, a su alta eficiencia de transporte (10-20%), en comparación con el nebulizador neumático (1-2%). El presente trabajo, demuestra la efectividad del nebulizador ultrasónico para mejorar los límites de detección del ICP OES axial. Para ello se aplicó inicialmente el método EPA 200.7, este método utiliza un nebulizador concéntrico (neumático) como parte del sistema de introducción de muestra del ICP OES (método A). Aplicando este método, se obtuvo un LDM de 0.0062 mg/L para arsénico y 0.0040 mg/L para plomo. Al utilizar el nebulizador ultrasónico acoplado al ICP OES axial (método B) se obtuvo un LDM de 0.0007 mg/L para arsénico y 0.0005 mg/L para plomo. Al comparar ambos métodos, se observa que el uso del nebulizador ultrasónico en conjunto con el ICP OES (método B), permite mejorar 8 veces los LDM de los elementos arsénico y plomo obtenidos con el método A. La veracidad del método fue comprobada, utilizando materiales de referencia certificados, marca ERA, en matrices tipo agua de consumo y agua residual. Los resultados de las pruebas t de 1 muestra, ejecutadas a través del software Minitab, muestran valores de P value > 0.05, esto nos permite concluir que los valores encontrados experimentalmente, son equivalentes estadísticamente a los valores certificados del material de referencia, concluyendo que el método B es veraz. / Tesis
145

Reactive Sputter Deposition of Lithium Phosphorus Oxynitride Thin Films, A Li Battery Solid State Electrolyte

Mani, Prabhu Doss 01 January 2015 (has links)
Lithium phosphorus oxy-nitride (LiPON) thin films are widely studied and used as a thin film electrolyte for lithium ion battery applications. LiPON thin films may be prepared by many techniques, but RF sputter deposition is most frequently used and was investigated in this dissertation, in spite of its low deposition rate, because of it offers more reliable and controllable processing. This dissertation includes the methodologies of sputter deposition and materials characterization of the LiPON thin film electrolytes. The LiPON thin films were deposited under varying conditions of process gas, substrate bias, and deposition temperature. To understand the variations in ionic conductivity observed, the films were extensively characterized to examine structural and compositional differences, including examination by x-ray photoelectron spectroscopy (XPS), inductively coupled plasma optical emission spectroscopy (ICP/OES), and spectroscopic ellipsometry. In addition, film density, and the intrinsic stress of the deposited films were also studied. The highest ionic conductivity of 9.8 x 10-6 S/cm was obtained at elevated deposition temperature and is correlated to a reduced density of defects, as indicated from the optical characterization.
146

Determination of Metallic Constituents in Environmental and Biological Materials

Johnson, Monique Erica 01 September 2012 (has links)
Studies of the interaction of the relevant metal, metalloid or nanoparticulate species with biological systems are underpinned by the provision of reliable information about chemical composition of the relevant materials. Often, no methods of chemical analysis are available. The work described in this dissertation centers on developing methods to help with studies for a variety of analytes and samples. A method was developed for the determination of 11 trace elements (As, Cd, Co, Cr, Cu, Fe, Mg, Mn, Pb, Ti, and Zn) in human breast milk and infant formulas by inductively coupled plasma optical emission spectrometry (ICP-OES) following microwave-assisted digestion. A method was established for the determination of trace elements, with an emphasis on titanium as titanium dioxide, in snack foods and consumer products. The interactions of some dissolved metals, including rare earth elements, and metallo-nanoparticles (silver, gold, titanium dioxide, aluminum oxide, and iron) with aquatic plants were studied. After exposure in a variety of mesocosms, the partitioning of the elemental species between various compartments was quantified by ICP-MS and ICP-OES following microwave-assisted digestion. An ICP mass spectrometry (MS) method has also been developed to quantify the uptake of gold and silver nanoparticles by C. elegans. Uptake of gold nanoparticles was size dependent, suggesting increased ingestion efficiency with increased particle diameter. The feasibility of discriminating between suspended TiO2 nanoparticles and dissolved titanium by the analysis of the rapid transient signal events obtained from the ICP-MS instrument operated in a rapid response mode was also developed. Data handling parameters were established that allowed a distinction in the signals for nanoparticulate and standard solutions. Spikes in the signal were defined by distinct parameters using the mean and standard deviation, where a spike in the signal was defined as a signal > + ks (k =3). This approach however did lead to a statistical difference in the spike signal events for solutions and nanosuspensions.
147

Determination and Speciation of Arsenic in Environmental and Biological Samples

Berg, Tiffany 01 September 2012 (has links)
A method was developed for the determination of total arsenic in rice grain by microwave-assisted digestion inductively coupled plasma mass spectrometry. Standard calibration solutions were matrix-matched with respect to acid concentration and carbon content post-digest. The importance of eliminating the drying step during sample preparation procedures was investigated. The method was validated with spikes containing standard arsenate solutions into the rice matrix, and with certified reference material SRM1568a (rice flour) from NIST. The method was successfully applied to a commercially available rice sample. Four arsenic species [arsenate (As(V)), arsenite (As(III)), dimethylarsinic acid (DMA) and monomethylarsonic acid (MMA)] were extracted from rice grains by microwave-assisted extraction and separated with high performance liquid chromatography inductively coupled plasma mass spectrometry. The method includes a novel sample clean-up step involving a dialysis procedure to decrease the amount of large starch molecules in the injection solution, in order to minimize poor resolution of chromatographic peaks and maximize column life. The method was validated with spikes of standard arsenic solutions, added to the rice matrix before the extraction procedure. Literature reference values for arsenic species quantification in SRM1568a (rice flour) were also compared. This method was successfully applied to a commercially available rice sample. A study into improvements in reverse phase-HPLC separations of arsenic species was conducted. For the first time, a Sunfire C8 column from Waters (Milford, CT) was employed for the separation of arsenic species in rice extracts. This column was compared to a Symmetry C8 column with respect to total elution time, detection limits, interference effects, and column life, and evaluated with respect to peak resolution, shifts in retention times, and peak symmetry.
148

Bottled Drinking Water: Assessment of Physical-Chemical and Microbiological Parameters and Biological Stability of 19 Different Brands Available in Saudi Arabia

Nadreen, Yasmeen 07 1900 (has links)
Bottled drinking water is a common form of water consumption that has grown in popularity and dependency. With countless types and brands available, there are factors to consider regarding the variations in mineral content and microbiological quality, and environmental consequences associated with importing natural bottled waters. Saudi Arabia is the largest desalinated water producer, and although there are scarce natural water resources, consuming locally produced water can alleviate environmental pressures, so long as local bottled water is of good quality and provides the basic function of drinking water. The objective of this study is to scrutinize the variations in bottled waters available in the Saudi market and compare local and imported waters regarding water quality and compliance with health regulations. Surveying local bottled waters revealed that over 60% were imported, adding to the environmental significance. Results from inductively coupled plasma-atomic emission spectroscopy, ion chromatography, and pH meters indicate most bottled waters were compliant with health standards. Flow Cytometry (FCM) was used to determine microbial cell densities. Purified waters, on average, contained significantly lower concentrations than other water types, while mineral waters contained the most cells per milliliter. Microbiological stability was examined through incubating samples at 30°C to promote microbial growth, and results were analyzed using an online FCM system. Purified waters had the least amount of growth and to a lesser degree than mineral and sparkling, which varied in microbial growth responses. DNA extractions and microbial community analyses were performed on select mineral waters before and after incubation. Results showed microbial genera found were similar between samples from the same country and some were unique. All samples exhibited some change in microbial community composition after incubation, signifying that certain communities thrived more than others. Proteobacteria was the most common abundant phylum among samples. Although analysis was restricted to the genera level, there were no health concern associated with types of bacteria discovered. In conclusion, local purified waters had greater microbiological quality and stability than imported waters, and mineral compositions were within the healthy range. Reducing reliance on foreign natural waters may help alleviate environmental consequences and improve local economy
149

Analyse von Kunststoffadditiven mittels Laserablation gekoppelt mit induktiv gekoppelter Plasma Massenspektrometrie

Börno, Fabian 29 November 2016 (has links)
Die Laserablation gekoppelt mit der Massenspektrometrie mit induktiv gekoppeltem Plasma ist eine vielversprechende direkte Feststofftechnik, die sich jedoch bei der Analyse von Kunststoffen wegen des Mangels an matrixangepassten zertifizierten Referenzmaterialien nicht durchsetzen konnte. Vorherige Arbeiten belegen polymerabhängige Abtragsraten. Das oft als interner Standard verwendete Intensitätssignal des Kohlenstoffisotopes 13C zur Korrektur dieser Unterschiede wird in der Literatur kritisch diskutiert. In dieser Arbeit als ein Teil des BMBF-geförderten MaxLaP-Projektes wurden matrixangepasste Standards auf Polyethylen- und Acrylnitril-Butadien-Styrolbasis entwickelt. In diese Standards wurden Br, Cd, Cu, Cr, Fe, Sb in organischer und anorganischer Form ihrer Verbindungen mittels Extrusion eingearbeitet. Die quantitative Zusammensetzung der Materialien wurde mittels ETV-ICP-OES, DC-arc-OES, RFA und ICP-MS nach Mikrowellendruckaufschluss überprüft. Die Verfahren wurden für die Kunststoffanalyse optimiert. Die mikroskopische Homogenität der Einarbeitung wurde mittels µ-SYRFA und LA-ICP-MS untersucht. Zur Untersuchung der Matrixeffekte während der LA-ICP-MS und der matrixunabhängigen Kalibrierung für Kunststoffe wurden der Einfluss der chemischen Verbindung der Additive, die Größe, der bei der Laserablation gebildeten Partikel und die Art des Kunststoffes auf die Laserablation analysiert. Die Korrektur des verschiedenen Materialabtrages über die Verwendung des 13C-Signals konnte für 21 verschiedene Kunststoffe erfolgreich durchgeführt werden. Allerdings zeigen die zugesetzten Additive ein nicht identisches Verhalten hinsichtlich Transport und Ionisierung. Weitere Ergebnisse belegen eine Anreicherung der Additive in verschiedenen Partikelgrößen sowie eine deutlich unterschiedliche Partikelbildung bei Ablationen von verschiedenen polymeren Matrices, was zu einer verstärkten Elementfraktionierung bei einer nicht matrixangepassten Kalibrierung führt. / Laser ablation coupled to a mass spectrometer with inductively coupled plasma (LA-ICP-MS) is a promising direct solid sampling technique. Due to the lack of matrix matched standard materials laser ablation is not well established in polymer analysis. In a recent study a polymer dependent interaction with the laser beam was reported, which resulted in a polymer depending ablation rate. The usage of the carbon-13-signal intensity as internal standard to correct these differences as commonly applied has been critically discussed in literature. In this work as part of a BMBF-supported MaxLaP-project (matrix effects during laser ablation of polymers) matrix matched standards based on polyethylene and acrylonitrile butadiene styrene were developed. In these materials Br, Cd, Cu, Cr, Fe and Sb were incorporated as organic and inorganic compounds through extrusion. Quantitative composition of the materials was determined by ETV-ICP-OES, DC-arc-OES, XRF and ICP-MS after high pressure microwave digestion. Analytical methods were optimized for trace analysis in plastic matrices. Microscopic homogeneity was examined by µ-SyXRF as well as LA-ICP-MS. In order to investigate the matrix effects and to determine the possibility of a matrix independent calibration for plastic materials, the influence of the chemical form of the additives, size of the formed particles and the type of the plastic on the LA-ICP-MS measurements were analyzed. The correction of the material uptake by the carbon-13-signal was successfully applied for 21 different types of plastic. However, different incorporated additives show a different transport and ionization behavior. Furthermore, our results confirm a different enrichment of the additives depending on particle size and a significantly different particle formation for different types of plastic, which leads to a more pronounced elemental fractionation by not using a matrix matched calibration.
150

Dissolução eletrolítica de ligas de alumínio em cavacos e determinação dos elementos constituintes por espectrometria de emissão atômica com fonte de pasma (ICP-OES) / Electrolytic dissolution of aluminum alloys (Chip form) and multi-element determination by inductively coupled plasma optical emission spectrometry (ICP-OES)

Grigoletto, Tânia 20 March 2001 (has links)
Várias ligas de Al em cavacos, com diferentes granulometrias foram dissolvidas de modo convencional, com ataque por água régia. Este tipo de decomposição resulta, muitas vezes, em resíduos sólidos, cujas quantidades dependem dos teores de silício. A fim de se comparar os resultados, procedeuse, com esses resíduos, de dois modos distintos: ou foram desprezados ou foram decompostos com ácido fluorídrico, eliminando-se o silício, dissolvendo-se o restante com ácido nítrico e agrupando-o à primeira solução para a determinação de Fe, Cu, Mn, Mg, Cr, Ni, Zn, Pb, Sn, Ti e Zr por ICP-OES. Foi avaliada a influência de quantidades crescentes de Al na determinação destes elementos e, também, a provável interferência espectral de Cu na determinação do Zn (com e sem separação eletrolítica de Cu). A dissolução eletrolítica de ligas de alumínio em cavacos foi estudada pressionando-os contra um eletrodo de platina para que se comportassem como se fossem o próprio ânodo e a eletrólise ocorresse. Uma célula foi construída utilizando-se um tubo (corpo de seringa de 2,5 mL) com perfurações ao redor da base aberta, onde foi colocada uma malha sintética (perlon) no fundo e, sobre esta, a amostra. Na parte superior foi introduzido um pequeno tarugo de acrílico com um fio de platina passando pelo seu interior e com um orifício por onde passava o fluxo (4,5 mL min.-1) da solução eletrolítica (ácido nítrico diluído). Na extremidade inferior, prendeu-se, com o fio, uma plaquinha, também de platina, que pressionava a amostra. A solução saía pelos orifícios inferiores para um béquer de onde era recirculada e onde estava colocado o cátodo, um fio de Pt (de forma de losango), sendo novamente captada e introduzida na parte superior do tarugo do ânodo. Com esse circuito, foram obtidos bons resultados utilizando-se ácido nítrico 1 mol L-1, corrente de 0,6A e tempo de eletrólise de 10 minutos. Sendo a dissolução parcial, é necessário que se conheçam as porcentagens dos elementos por dissolução ácida total de uma liga de composição similar ou por um material de referência certificado. Normalizaram-se os dados pelas porcentagens conhecidas dos constituintes das ligas. Compararam-se os cálculos feitos dos seguintes modos: 1-) pela razão entre a concentração do elemento com a do Al, também determinada; 2-) pela a razão entre a concentração do elemento com a soma das concentrações de todos os elementos determinados, inclusive o Al; 3-) pela razão entre a concentração do elemento e a soma das concentrações só dos outros elementos, sem o Al. O desvio padrão e o erro relativo para os elementos Fe, Cu, Mg, Ni e Cr, quando em teores > 0,1%, foram < 10%; para teores de Zn < 0,2%, foram menores de 10% e para teor de 4,8% foram < 15%. Já para o Mn, quando em teor > 0,2% foram <10% (exceto para a liga B.C.S.268/1). O desvio padrão relativo para o Zr, com teor ao redor de 0,002% foi <10%. Os resultados para o elemento Pb nas ligas B.C.S. 216/1 e 380 tiveram desvio padrão e erro relativo <10%, mas o mesmo não ocorreu na liga B.C.S. 268/1. O elemento Sn apresentou resultados piores, ao redor de 20%. O elemento Ti só deu bons resultados quando em teor de cerca de 0,2%. Para estas determinações foram avaliadas as dissoluções químicas dos metais nas ligas pelo ácido nítrico em diferentes concentrações e temperaturas. Além disso, foram avaliadas duas outras células para a verificação da possibilidade de dissolução eletrolítica das ligas de Al on-line com a determinação por ICP-OES. / Several aluminum alloys with different chips size were dissolved using aqua regia (HCl:HNO3,3:1). The residues of the dissolution procedure were either rejected or used in silicon volatilization with hydrofluoric acid before determination of Fe, Cu, Mn, Mg, Cr, Ni, Zn, Pb, Sn, Ti and Zr by ICP-OES. The influence caused by crescent amounts of aluminum in the determination of other elements and the probable spectral interference by Cu in determination of Zn (with or without electrolytic separation of Cu) was evaluated. The electrolytic dissolution of aluminum alloys was performed by pressing chips against a platinum electrode for the electrolysis to occur, so that way the chips behaved as the anode. A tube (body of syringe of 2.5mL) with perforations around the open base was used to contain the sample and Pt electrode. The alloy was placed on synthetic wool (perlon) in this tube. An acrylic dowel with a platinum wire across its interior was fixed in the superior part a tube with Teflon film, with an orifice through which the electrolytic solution flowed (HNO3 1 mol L-1; 4.5mL min-1). A platinum dish was fixed at the inferior extremity of the platinum wire to press the sample. The solution came out through the inferior orifices of the tube to a flask, from where it was again captured (with a peristaltic pump) to go into the superior part of the tube. In this flask, a Pt wire cathode was also placed. A current of 0,6A and ten minutes of electrolysis provided good results. Due to the partial dissolution, the knowledge of percentages of previous elements analyzed after total dissolution, or using certified reference material are necessary. The results were normalized by known percentages. The calculations were made by: 1-) the ratio between the concentration of the element determind, with the determined concentration of aluminum; 2-) the ratio between concentration of the element and the sum of the concentrations of the elements determined, including Al; 3-) the ratio between the concentration of element and the sum of the concentrations of the elements determined, without the aluminum. The relative standard deviations and accuracy were <10% for the elements Fe, Cu, Mg, Ni and Cr when the concentrations were >0.1%; for the Zn were 15%, when the concentration >0.2%, and <10% for concentration <0.2%. For Ti with concentration of about 0.1%, were 15%. Relative standards deviations for the Zr, with concentration of 0.002%, were always <10%. The element Pb, Sn and Mn didnt provide good results. For these determinations, the chemical dissolution of the elements with different nitric acid concentrations and temperature was evaluated. Two other cells for the electrolytic dissolution of Al alloys followed by online ICP-OES determination were examined.

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