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No. of bitstreams: 1 DissFCP.pdf: 872515 bytes, checksum: 9999d59df5e906241a9e5c0ad54a27a7 (MD5) Previous issue date: 2016-07-07 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Analytical procedures using inductively coupled plasma mass spectrometry (ICP-MS) for the determination of total As in rice samples and fruit juices and inorganic As in rice samples were developed. A microwave-assisted digestion procedure carried out in closed vessels was developed using hydrogen peroxide and dilute nitric acid for better control of the analytical blank. The selective extraction procedure used for the determination of inorganic As was characterized by its simplicity and use of non-toxic reagents. Inductively ICP-MS/MS in mass-shift mode was efficient for the determination of total As in juices samples by reaction of the analyte with oxygen, enabling the determination of arsenic without interferences by monitoring 75As16O+. The limit of detection was 0.013 μg L-1 and total As concentrations determined in juices ranged from 0.126 to 1.45 μg L-1. All samples had As concentrations significantly lower than the maximum tolerable limits imposed by legislation. Addition and recovery experiments performed in reactive gas operating mode led to quantitative recoveries showing the accuracy of the procedure. Determination of total and inorganic As in rice samples were performed using ICP-MS in acquisition mode with and without collision cell pressurized with He flow rate at 4.5 mL min-1. The limit of detection without collision gas acquisition mode was in the range of 0.005 a 0.007 mg kg-1. Recovery was 103 % for total As content certified for NIST 1568a rice flour. The total As concentrations in rice samples ranged from 0.073 to 0.665 mg kg-1 with a mean content of 0.278 mg kg-1. Three different types of rice grains had higher concentrations than the maximum tolerable level 0.30 mg kg-1 of total As imposed by ANVISA, FAO and WHO. The inorganic As determination procedure had detection limit ranged from 0.05 to 0.06 μg kg-1 and mean concentrations of 0.079 mg kg-1 for rice samples. All samples had inorganic As concentrations lower than the maximum tolerable limit 0.20 mg kg-1 imposed by FAO and WHO, except brown rice sample. The total and inorganic As concentrations higher than those allowed in legislations indicate the relevance of As monitoring in rice and the need to improve the Brazilian legislation which so far does not have a regulation for inorganic As. / Neste trabalho foram desenvolvidos procedimentos analíticos usando espectrometria de massas com plasma acoplado indutivamente (ICP-MS) para a determinação de As total em amostras de arroz e sucos de frutas e As inorgânico em amostras de arroz. O procedimento de digestão das amostras foi conduzido em frascos fechados assistido por radiação micro-ondas empregando-se solução de H2O2 e ácido nítrico diluído, condição favorável para o controle do branco analítico. O procedimento de extração seletiva adotado para a determinação de As inorgânico se caracterizou pela praticidade e emprego de reagentes pouco tóxicos. O ICP-MS/MS em modo de operação mass-shift foi eficiente para a determinação de As total nas amostras de sucos pela reação do analito com oxigênio, possibilitando a determinação de As isenta de interferências monitorando-se a espécie 75As16O+. O limite de detecção do procedimento foi de 0,013 μg L-1 e as concentrações de As total determinadas nos sucos variaram de 0,126 a 1,45 μg L-1, sendo significativamente inferiores aos limites máximos toleráveis impostos pelas legislações. As recuperações quantitativas obtidas no experimento de adição e recuperação realizado em modo de operação com gás reacional possibilitaram inferir sobre a exatidão do procedimento. As determinações de As total e inorgânico nas amostras de arroz foram realizadas empregando o equipamento ICP-MS no modo de aquisição sem e com cela de colisão pressurizada com He na vazão otimizada de 4,5 mL min-1. O limite de detecção em modo de aquisição sem gás de colisão apresentou-se na faixa de 0,005 a 0,007 mg kg-1 com recuperação de 103 % referente ao teor de As total certificado para o material de referência certificado NIST 1568a farinha de arroz. As concentrações de As total para as amostras de arroz analisadas variaram de 0,073 a 0,665 mg kg-1 com média de 0,278 mg kg-1. Três diferentes tipos de grãos de arroz apresentaram concentrações superiores ao teor máximo tolerável de 0,30 mg kg-1 de As total imposto pela ANVISA, FAO e WHO. O procedimento de determinação de As inorgânico apresentou limite de detecção na faixa de 0,05 a 0,06 μg kg-1 e teor médio de 0,079 mg kg-1 para as amostras de arroz. Todas as amostras apresentaram concentrações de As inorgânico inferiores ao limite máximo tolerável de 0,20 mg kg-1 imposto pela FAO e WHO, com exceção da amostra de arroz integral. As concentrações de As total e inorgânico superiores às permitidas nas legislações atestam a relevância do monitoramento de As em arroz assim como a necessidade de aperfeiçoamento da legislação brasileira, que não apresenta regulamento para As inorgânico.

Abstract Humus-rich natural water samples, containing high concentrations of dissolved organic carbon (DOC), are challenging for certain analytical methods used in trace element analysis, including hydride generation methods and electrochemical methods. In order to obtain reliable results, the samples must to be pretreated to release analytes from humic acid complexes prior to the determination. In this study, methods for both pretreatment and analysis steps were developed. Arsenic is a toxic element and therefore its determination even at low concentration levels is important in environmental monitoring. Arsenic complexed with humic substances is not likely to form volatile hydrides quantitatively during borohydride reduction. In this study, natural water samples were digested with microwave-assisted digestion method prior to analysis by hydride generation inductively coupled plasma mass spectrometry (HG-ICP-MS). In addition, a dual mode sample introduction system was used to study internal standardization in order to correct signal variations during the measurement of arsenic with HG-ICP-MS. A novel nano-TiO2 catalyzed ultraviolet light emitting diode (UV-LED) digestion device was developed to apply green chemistry principles in sample preparation. The method consumes less harmful reagents and less energy than traditional techniques. The DOC removal efficiency was studied as a function of pH, irradiation time and hydrogen peroxide concentration. Recoveries of spiked heavy metals and hydride forming elements were studied. UV-LED technology is growing rapidly, and new catalytic semiconductor materials for photocatalysis are being developed. In this study, the effects of synthesis method variables on the properties of ZnO nanopowders were investigated. / Tiivistelmä Luonnonvesinäytteet voivat sisältää suuria määriä liuennutta hiiltä (DOC), jolloin pienten alkuainepitoisuuksien määrittäminen voi olla haasteellista esimerkiksi hydridinmuodostusmenetelmillä ja sähkökemiallisilla menetelmillä. Luotettavien tulosten saavuttamiseksi näytteet täytyy esikäsitellä analyyttien vapauttamiseksi humushappokomplekseista ennen määrityksiä. Tässä tutkimuksessa kehitettiin menetelmiä humuspitoisille luonnonvesinäytteille sekä esikäsittelyvaiheeseen että analyysivaiheeseen. Arseeni on myrkyllinen alkuaine, jonka määrittäminen pienissä pitoisuuksissa on ympäristön seurannan kannalta tärkeää. Humusyhdisteisiin kompleksoitunut arseeni ei muodosta kvantitatiivisesti hydridejä borohydridipelkistyksellä. Tässä tutkimuksessa luonnonvesinäytteet hajotettiin mikroaaltoavusteisella hajotusmenetelmällä ennen arseenin mittaamista hydridinmuodostus-induktiiviplasmamassaspektrometrialla (HG-ICP-MS). Tämän lisäksi tutkittiin mittaustarkkuuden parantamista sisäisellä standardoinnilla mitattaessa arseenia HG-ICP-MS-menetelmällä. Tutkimuksessa kehitettiin myös uudenlainen näytteenkäsittelylaitteisto, jossa käytettiin säteilylähteenä ultraviolettivaloa emittoivaa diodia (UV-LED) ja katalyyttinä nanotitaanidioksidia. Uusi ympäristöystävällinen menetelmä kuluttaa vähemmän haitallisia reagensseja ja vähemmän energiaa kuin perinteiset menetelmät. Kehitetyn menetelmän hajotustehokkuutta tutkittiin pH:n, säteilytysajan ja vetyperoksidikonsentraation funktiona. Lisäksi raskasmetallien ja hydridiä muodostavien alkuaineiden saantoja tutkittiin lisäyskokeilla. UV-LED-teknologia kehittyy nopeasti ja uusia valokatalyysimateriaaleja tutkitaan jatkuvasti. Tässä tutkimuksessa tarkasteltiin synteesimuuttujien vaikutusta sinkkioksidinanojauheiden ominaisuuksiin.

The aim of the diploma thesis was to provide an overview of the prevalence of allergenic and potentially allergenic metals in eye shadows. The diploma thesis gives an overview of the legislation on cosmetics and description of the types of allergenic reactions caused by allergenic and potential allergenic metals in eye shadows. Listed below are the preparation methods of the samples for analysis and the list of the methods by which can the selected metals be analyzed. The experimental part of the diploma thesis deals with an analysis of selected allergenic and potentially allergenic metals in eye shadows. In the experimental part of diploma thesis method of sample preparation for analysis of eye shadows and a method of analysis of sample of eye shadows by ICP-MS have been optimized. Monitored analytes were selected metals. Altogether 6 samples of eye shadows from different manufacturers were chosen. Measured results have been statistically processed, confronted with the applicable legislation and assessed in terms of possible allergic reactions.

The present PhD is focused on the development of new analytical methods based on ICP techniques to carry out the elemental and isotopic analysis of bioethanol samples and other specimens taken along the bioethanol production process. The total sample consumption system, so-called hTISIS, has been used as sample introduction system in ICP-OES for the quantification of major and minor metals, and ICP-MS for the determination of trace metals. The hTISIS has also been successfully set up to carry out the lead isotopic analysis of bioethanol samples. Additionally, metals found in bioethanol have been monitored along the production process of this biofuel to identify the origin of these metals. Finally, volatile organic compounds have been determined in different bioethanol samples to perform the characterization of the matrices and their effect on the accuracy of the methods based on ICP techniques, developed in the present PhD for the elemental and isotopic analysis of these kind of samples. / La presente Tesis Doctoral se centra en el desarrollo de nuevos métodos de análisis basados en técnicas de ICP para llevar a cabo el análisis elemental e isotópico de muestras de bioetanol y muestras tomadas a lo largo del proceso de obtención de dicho biocombustible. Se ha empleado un sistema de consumo total de muestra, conocido como hTISIS, como sistema de introducción de muestras en ICP-OES para la cuantificación de metales mayoritarios y minoritarios, y en ICP-MS para la determinación de metales traza en bioetanol. El sistema hTISIS también se ha empleado con éxito para llevar a cabo el análisis isotópico de plomo en dichas muestras. Además, los metales encontrados en las muestras de bioetanol han sido monitorizados a lo largo del proceso de obtención del mismo para identificar el origen de dichos metales. Finalmente, se han determinado los compuestos volátiles presentes en diferentes muestras de bioetanol, con el objetivo de caracterizar las matrices y como estas pueden afectar a la exactitud de los métodos desarrollados, que emplean técnicas ICP para el análisis elemental e isotópico de este tipo de muestras.

The aim of this study was to determine the occurrence of selected toxic elements in wine. The theoretical part described technology of wine production and selected toxic elements (cadmium, lead, copper, zinc, nickel and chromium) in the terms of their impact on wine quality and their effects on the human organism. It provides an overview of instrumental analytical methods, which can be used for the analysis of toxic metals. In the experimental part inductively coupled mass spektrometry technique was used for the analysis of wine samples. The measured values are statistically processed and compared with current legislation.

The determination of inorganic speciations of arsenic, antimony, selenium and tellurium in natural waters demands often separation and preconcentration. Solid phase extraction is a very effective method for these purposes. In this paper the separation and preconcentration of these microelements is realised on the basis of modified silica Separon SGX C18, SGX C8, SGX CN, SGX NH2, SGX Phenyl and strongly basic anion Exchanger SGX AX. The sorption was provided in the presence of cationic surfactants such as benzyldimethyl dodecylammonium bromide (Ajatin), benzyldimethyltetradecylammonium chloride (Zephyramine), 1-ethoxycarbonylpentadecyltrimetrhylammonium bromide (Septonex) and selected complexing agents 4-(2-pyridylazo)resorcinol (PAR), 8-hydroxyquinoline-5-sulphonic acide (8-HQS), 1,2-dihydroxybenzene (PYR), amonium 1-pyrrolidinecarbodithioate (APDC), sodium diethyldithiocarbamate (DTC) or thiourea(Thur). The interactions of the formed ion associate with the sorbent shows a complicated character which has not been cleared as yet. The previous conditioning of the sorbent plays an outstanding role. Thus, the sorption efficiency was studied in the presence and absence of surfactant and of selected organic complexing agents. Moreover, the influence of pH of the sorbed solution as well as the speed and the volume of the solution running through the sorbent and the type and volume of the eluent on the resulting sorption efficiency was evaluated. The sorption was successfully carried out from 50-1000 ml of solution which allows the 100 fold increase of the preconcentration factor and the determination of the microelements in g.l-1 instead of mg.l-1 by using the common ICP-AES. The influence of macroelements occurring in waters as well as B, Be, Bi, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Sr, Ti, V and Zn in comparable concentrations involve less than 5% error. After the quantitative elution of microelements, the organic solvents were evaporated under IR lamps prior to the determination by ICP-AES and |ICP-MS. The conditions for the direct determination of arsenic, antimony, selenium and tellurium in g.l-1 with ICP-MS were also described in detail in the absence and presence of internal standards Ge and Bi. However, even in this case the preconcentration on silica in the presence of surfactant and selected organic complexants was also tested. When the sorption was followed from 500 ml a 50 fold enrichment factor is reached and the sensitivity for the microelements is improved. The direct determination and the sorption of microelements were applied on synthetic and real waters (dirinking, surface, mineral and sea waters). Instrumental and practical detection limits for various water samples were evaluated according to IUPAC. The results from 1000 ml solution of real waters after sorption on modified silica and the final determination of microelements with ICP-AES were compared with those from ICP-MS without sorption using the method of standards addition in the presence of suitable internal standards. By comparison of results for synthetic and real water samples the error of the determination of microelements was evaluated.

No description available.

Late-stage fissure-filling ore at the world class Bingham Canyon, Utah, porphyry copper deposit has long been recognized, but poorly studied. Physical and chemical characterization of the Pb-Zn-Cu-Ag-Au mineralized fissures in the porphyry-epithermal transition zone provides insight into the origin, timing, and controls of ore deposition. These sheared sulfide-rich fissures are dominated by pyrite and multiple generations of quartz, with lesser amounts of other sulfides and gangue minerals. Au (0.27 to 4.61 ppm) provides the most value to the ore in the transition zone. Host rocks include Eocene monzonite and Paleozoic limestone and quartzite"”all of which can contain economic ore bodies. Associated alteration is predominantly sericitic and argillic. Mineralization into the wall rocks is restricted, not exceeding 1.5 m from the fissure margins. Mineral assemblages vary with distance from the center of the main Cu-Mo deposit and the modal abundances are dependent on host rock. The appearance of both galena and sphalerite (and tennantite to an extent) mark the transition from a porphyry to an epithermal environment. This is accompanied by an increased concentration of chalcophile trace elements in sulfides as determined by EMPA and LA-ICP-MS. Significant hosts of Ag include galena and tennantite, while Cu is hosted primarily in chalcopyrite, tennantite, and sphalerite. Gold does not appear to be hosted in solid solution, but may be focused along fractures or inclusions in pyrite. δ3434S values of fissure pyrite has a narrow range (+2.3 to 3.4‰), while δ18O of quartz is more variable and high (+11.5 to 14.0‰) relative to typical hydrothermal quartz. This can be explained by increased fractionation at lower temperatures in the magmatic fluids, which could have additionally mixed with exchanged 18O-rich meteoric water. Ore grades improve with distance from the center of the deposit; however, this is accompanied by higher concentrations of elements (Pb, As, Bi, etc.) undesirable for downstream processing. The mineralized fissures were created sequentially throughout the formation of the deposit. Initial joints probably formed as a result of the intrusion of a barren equigranular monzonite. The NE orientation of the joints was controlled by the regional stress field, which is more apparent distal to the center of the deposit. A quartz monzonite porphyry then intruded, dilating the joints to allow precipitation of quartz and then pyrite during the Cu-Au-stage of mineralization in the main ore body. After dike-like intrusions of latite porphyry and quartz latite porphyry intruded, galena, sphalerite, and pyrite precipitated to form the Pb-Zn-Ag mineralization. This was followed by late precipitation of chalcopyrite and tennantite (and likely Au mineralization).

The exposed metamorphic core complexes in the Cyclades continental back-arc of southeast Greece host a range of base and precious metal deposits. Shallow crustal mineral deposits that formed since the late Miocene to active seafloor hydrothermal systems occur in the footwall and hanging wall of the major detachment systems and within all tectono-stratigraphic units. The carbonate-replacement, vein-type, intermediate-sulfidation epithermal, and skarn deposits tapped different sources of metals and fluids along the major low-angle detachment systems and steep normal faults. This study links the regional metallogenic diversity to fluid and crustal sources, within a framework of the evolving geodynamic context and complex basement structure. Over 30 mineral occurrences, from Lavrion of Attica on the Greek mainland across the Cycladic archipelago to Milos and Santorini on the active South Aegean volcanic arc, were investigated, encompassing ~40,000 km2 of the arc- to backarc system. Petrographic observations are combined with mineralogical, geochemical, and isotopic analyses (Pb, Sr, δ34S and δ18O) of galena (PbS) and ore-associated hydrothermal barite (BaSO4). New galena Pb isotope data complemented by Pb isotope data of galena from the literature exhibit a range of isotopic ratios, with a resolvable geologic pattern. Galena from deposits in the north-central Cyclades has low 206Pb/204Pb ≤18.84, while galena from the west Cyclades has higher 206Pb/204Pb ≥18.84. This distinct regional pattern is further supported by the Sr isotope signature of hydrothermal barite, with 87Sr/86Sr ≥0.711 in the north-central Cyclades and 87Sr/86Sr  ≤0.711 in the west Cyclades. When considered together with compiled Pb and Sr isotope data of potential source rocks, large-scale regional patterns in the isotopic signatures are recognized, suggesting two distinct sources of lead and strontium in the underlying basement of the core complexes. These two sources (Lower Cycladic Blueschist Nappe and Upper Cycladic Blueschist Nappe including the Cycladic Basement) correspond to known tectono-stratigraphic units of different provenance and age and help to correlate the basement over considerable distances, even where exposures are limited. Sulfur and oxygen isotope data of barite indicate variable contributions of sulfur from seawater and magmatic fluids among the range of deposit types. This indicates that different fluid generations evolved and tapped the basement, likely along the major detachment faults. The δ34S values of barite indicate that mineral deposits in the Cyclades can be clearly distinguished. Compiled whole-rock isotopic and geochemical data of the basement lithologies exhibit a broad dispersion. Miocene to recent mineralization in the Cyclades caused homogenization of the crustal sources and indicate regional lithological differences in the architecture of the exposed metamorphic core complexes. This thesis demonstrates that regional studies of the geochemical and isotopic composition of mineral deposits can provide additional constraints for the paleogeographic reconstruction of juxtaposed tectono-stratigraphic units across the Cyclades and other complex continental back-arc systems.

No description available.