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Orientador: Antonio José Ranalli Nardy / Banca: Maria Margarita Torres Moreno / Banca: Amauri Antonio Menegário / Resumo: No presente trabalho são descritas as etapas para o desenvolvimento de uma metodologia para determinação de arsênio, antimônio e bismuto em materiais geológicos, utilizando gerador de hidretos acoplado ao ICPOES, proporcionando a determinação dos elementos de interesse em baixas concentrações. O método é sensível, por isso está sujeito a interferências, como as causadas por elementos presentes na matriz. Foram realizadas otimizações nos parâmetros operacionais e analíticos do equipamento, que visaram uma melhor sensibilidade e um método eficiente de solubilização completa de amostra de rocha, que permita a determinação dos elementos de interesse em baixas concentrações. Para a etapa de validação do método foram realizados diversos ataques com adições de padrão e testes com o uso de tiouréia e iodeto de potássio com ácido ascórbico em diferentes concentrações com o objetivo de minimizar possíveis interferências presentes na matriz. Os resultados finais foram obtidos através da solubilização de materiais de referência internacionais geológicos na determinação de arsênio, bismuto e antimônio e se mostraram satisfatórios. / Abstract: In this study, the steps for the development of a methodology to the determination of arsenic, antimony and bismuth in geological materials, with the use of hydride generation and ICPOES are being described. The methodology is sensitive due to that, subject is bound to suffer interferences from matrix elements. Optimizations in operations and analyticals parameters were done in the equipment. They aimed a better sensitivite and an efficient method of complete dissolution techniques in a sample of rock, which permits the determination of the analyte in low concentrations. For the steps of methodology validation, many dissolutions were realized with the addition of standard and tests with the use of thiourea and KI and acid ascorbic in different concentrations with the objective of minimizing some interferences from matrix elements. The final results were obtained through dissolutions with international reference materials in the determination of arsenic, antimony and bismuth. / Mestre

Orientador: Marco Aurélio Zezzi Arruda / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-22T10:57:39Z (GMT). No. of bitstreams: 1 Galazzi_RodrigoMoretto_M.pdf: 2262907 bytes, checksum: fb6e92051f6858cd925c525071ce6540 (MD5) Previous issue date: 2013 / Resumo: Nessa dissertação, otimizou-se um método para a determinação de estanho (Sn) em amostras biológicas empregando a técnica de Espectrometria de Absorção Atômica por Geração de Hidretos e Forno Metálico (MF-HG-AAS, do inglês Metallic Furnace Hydride Generation Atomic Absorption Spectrometry). Foram avaliadas algumas variáveis químicas como o tipo e concentração do carregador/diluente da solução padrão, concentração do redutor tetraidridoborato (-1) de sódio (THB) e concentração de hidróxido de sódio, bem como variáveis físicas do sistema dentre elas a vazão de carregador, proporção de acetileno:ar na chama, volume de solução injetado, vazão de argônio como gás de arraste, vazão de água no nebulizador e área total de furos no tubo metalico Inconel600®. Foi realizado um estudo do efeito de memória observado em condições de chama oxidante nas vazões de 1,5:9; 1,4:9; 1,3:9; 1,4:10; 1,4:8 e 1,5:11 L min de acetileno:ar, respectivamente. Em todas essas proporções de chama diferentes da otimizada (1,5:10 L min acetileno:ar) há efeito de memória, o que é extremamente indesejável. Após a otimização do sistema, foram realizados testes de exatidão e precisão do mesmo com os materiais PACS-2 (sedimento) e SRM 1643e (amostra de água) em que, em ambos, foi possível recuperar o Sn adicionado obtendo limites de detecção (LD) de 7,1 mg kg e 7,6 mg L, respectivamente. Um estudo com concomitantes foi realizado para avaliar se algum dos elementos em questão poderia interferir na determinação do Sn. Foram estudados como possíveis concomitantes o cobre, chumbo e zinco em três níveis diferentes. Somente o cobre, nas razões de 1:10 e 1:20 (Sn:concomitante), interferiu na detecção de Sn. Por fim, a morfologia do atomizador foi avaliada por meio da técnica de Microscopia Eletrônica de Varredura (SEM, do inglês Scanning Electron Microscopy). Mesmo após a realização de todos os experimentos envolvendo a otimização do sistema e análise das amostras, os principais constituintes do tubo metálico Inconel600® (ferro, níquel e cromo) permaneceram homogeneamente distribuídos, indicando que esses metais podem não participar da rota de atomização do Sn. Além disso, houve formação de óxidos no atomizador que, juntamente com o uso de uma chama oxidante, sugerem uma rota de atomização do Sn via formação de óxidos. Considerando os LD, bem como a exatidão e precisão por meio da recuperação de Sn obtida nas amostras, constata-se a potencialidade da MF-HG-AAS frente a outras técnicas empregadas na determinação de Sn / Abstract: In this work, a Metallic Furnace Hydride Generation Atomic Absorption Spectrometry (MF-HG-AAS) was optimized for tin (Sn) determination in biological samples. Chemical variables, such as the type and carrier concentration, the sodium tetrahydrideborate (-1) (THB), and the sodium hydroxide concentration, as well as physical variables, such as carrier flow-rate, ratio of acetylene and air in the flame, injection volume, argon flow-rate as carrier of stannane, water flow-rate in nebulizer and total hole area of a Inconel600® metallic furnace were evaluated. A study of a memory effect observed in oxidant flame conditions such as 1.5:9; 1.4:9; 1.3:9; 1.4:10; 1.4:8 e 1.5:11 L minof acetylene:air, respectively, was realized. In any other flame flow-rate, which the optimized flame ratio (1.5:10 L min acetylene:air) was observed a memory effect, which is very undesirable. After optimizing of the system, test of accuracy and precision were realized with the PACS-2 (sediment) and SRM 1643e (water sample) materials wherein, in both, a recovery of the Sn added to the samples was possible with limits of detection (LOD) as 7,1 mg kg and 7,6 mg L, respectively. A concomitant study was carried out for checking the interferences in the Sn determination. Copper, lead and zinc at three different levels were studied as possible concomitants. Only copper, at 1:10 and 1:20 (Sn:concomitant) ratios interfered in the determination of Sn. Finally, the morphology of the atomizer employed was evaluated through Scanning Electron Microscopy (SEM) technique. Even after carrying out all experiments involved in the optimization of the system and in the sample analysis, the main constituents of Inconel600® metallic furnace (iron, nickel and chromium) remained homogeneously distributed, indicating which these elements may not participate of the Sn atomization route. Moreover, the oxide formation in the atomizer was detected, which, together with an oxidant flame used, suggests the Sn atomization route via oxides formation. Considering the LOD, as well the accuracy and precision through the Sn recovery in the samples, the MF-HG-AAS potentially is well pointed out when it is compared to other techniques employed for Sn determination / Mestrado / Quimica Analitica / Mestre em Química

This thesis develops high-performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-HG-ICP-MS) method used for the analysis of glutathione arsenic complexes in biological samples. The aim of the thesis was to verify the suitability of this methods and to perform pilot studies on analysis of the enzymatic methylation assay containing glutathione and urine. Inclusion of post-column hydride generation step resolves the problem of changing sensitivity of ICP-MS with gradient elution. Using the standards of glutathione complexes, it was verified that the HPLC-HG-ICP-MS method can provide both qualitative and quantitative analysis of these complexes. The limit of detection was found at 5 pg/ml. Analysis of the methylation assay of arsenic with glutathione showed that only DMAsGS complex occurs in the assay during methylation. It was verified that the presence of the enzyme is required for the complex formation. In the samples of urine from unexposed people analyzed by HPLC- HG-ICP-MS and hydride generation-cryotrapping-inductively coupled plasma mass spectrometry (HG-CT-ICP-MS), only the presence of free pentavalent arsenic species was found, whereas neither glutathione complexes nor trivalent species could be observed.

Electrochemical hydride generation is an alternative technique to the chemical hydride generation by NaBH4 which is widely used for atomic spectrometric determination of volatile elements such as As, Bi, Ge, Pb, Sb, Se, Sn and Te. The aim of this research has been to develop an analytical technique at the level of ng/L for determination of antimony by using a simple and inexpensive AA spectrometer and the other parts that can be built in any laboratory. Carbon rod and platinum foil were used as cathode and anode materials, respectively, for the generation of antimony hydride. Argon was used as the carrier gas. Zr coated W-coil was used for on-line preconcentration of generated hydrides. A new apparatus independent from quartz T-tube atomizer was constructed and used to contain the atom trap. Zr coated W-trap was heated to the collection temperature for trapping the analyte species generated electrochemically. For the revolatilization of the trapped species, the trap was further heated to the revolatilization temperature. Revolatilized species were transported to a flame-heated quartz tube atomizer where the analytical signal was recorded. Duringcollection and revolatilization steps hydrogen gas was introduced into the system to prevent the oxidation of atom trap. The experimental operation conditions for electrochemical hydride generation and atom trapping were optimized. 3&amp / #963 / limit of detections were found to be 0.012 ng/mL and 0.41 ng/mL with and without using trap, respectively. The trap has provided 34 fold sensitivity improvement as compared with the electrochemical hydride generation alone. The interferences of some hydride forming elements and some transition metals on electrochemical hydride generation with and without employing the trap were investigated. Analysis of standard reference material was performed to check the accuracy of the proposed method.

Antimony is a toxic element which is mostly found in two oxidation states (III and V) in environmental, biological and geological samples. Antimony may form various inorganic and organic compounds that exhibit differences in analytical behavior, toxicity and mobility / inorganic compounds of antimony are more toxic than organic forms and toxicity of Sb(III) has been shown to be 10 times higher than that of Sb(V). Therefore selective determination of Sb(III) and Sb(V) is required in environmental and biological samples. Hydride generation atomic absorption spectrometry is a sensitive, fast and economical technique for the determination of antimony at trace level. A possible non-chromatographic method for antimony speciation is hydride generation atomic absorption spectrometry that is based on the relatively slow kinetics of hydride formation from Sb(V). In this study, continuous flow hydride generation method for the determination of antimony was developed and hydride generation conditions were optimized. Analyte solution was prepared in 0.050 mol/L HCl and 1.2% (w/v) NaBH4 stabilized in 0.30% (w/v) NaOH was used as a reductant solution. Inorganic antimony speciation conditions were determined by continuous flow HGAAS system. For the pre-reduction of Sb(V) to Sb(III), 8.0% (w/v) potassium iodide (KI) and 0.10% (w/v) ascorbic acid were used. Further speciation study was also carried out using Ir coated W-coil Atom Trap Hydride Generation Atomic Absorption Spectrometry. Tungsten coil atom trap was used to enhance the sensitivity. Tungsten coil surface was treated with Ir and totally 250 &amp / #956 / g 1000 mg/L Ir stock solution was used for coating of tungsten coil. LOD and LOQ values were calculated as 152 pg/mL and 508 pg/mL according to 120 seconds trapping. 128 and 37 fold enhancement were obtained for 120 seconds collection with respect to W-coil-ETAAS and ETAAS, respectively.

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ABSTRACT ELECTROCHEMICAL HYDRIDE GENERATION AND ATOM TRAPPING ATOMIC ABSORPTION SPECTROMETRY FOR DETERMINATION OF ANTIMONY Menemenlioglu, ipek M.S., Department of Chemistry Supervisor: Prof. Dr. O. Yavuz Ataman June 2004, 82 pages Electrochemical hydride generation is a suitable alternative to common hydride generation by NaBH4 which is widely used for the detection of volatile elements such as As, Se, Sb, Sn, Bi, Ge, Te and Pb. In this study, a thin-layer flow through electrochemical cell was designed. Lead and platinum foils were employed as cathode and anode materials, respectively, for the generation of antimony hydride. Argon was used as the carrier gas. The inlet arm of the conventional quartz tube atomizer was used for on-line preconcentration of generated hydrides. A portion of the inlet arm was heated externally to the collection temperature for trapping the analyte species which were generated electrochemically. For the revolatilization of the trapped species, the trap was further heated to the revolatilization temperature and hydrogen gas was introduced into the system 10 seconds afterwards. The experimental operation conditions for electrochemical hydride generation which include the acidities and flow rates of catholyte and anolyte solutions, carrier gas flow rate and the applied electric current, were optimized. For trapping, collection and revolatilization temperatures and hydrogen flow rates were optimized. Analyses of standard reference materials were performed to check the accuracy of the proposed method. 3&amp / #963 / limit of detections were found as 1.03 ng ml-1 and 0.053 ng ml-1 with and without employing the trap, respectively. The trap has provided 20 fold sensitivity improvement.

Made available in DSpace on 2014-06-11T19:26:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-05-06Bitstream added on 2014-06-13T19:33:35Z : No. of bitstreams: 1 borges_em_me_rcla.pdf: 583445 bytes, checksum: a94bcee1df858747cf63f7c61d62429e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / No presente trabalho são descritas as etapas para o desenvolvimento de uma metodologia para determinação de arsênio, antimônio e bismuto em materiais geológicos, utilizando gerador de hidretos acoplado ao ICPOES, proporcionando a determinação dos elementos de interesse em baixas concentrações. O método é sensível, por isso está sujeito a interferências, como as causadas por elementos presentes na matriz. Foram realizadas otimizações nos parâmetros operacionais e analíticos do equipamento, que visaram uma melhor sensibilidade e um método eficiente de solubilização completa de amostra de rocha, que permita a determinação dos elementos de interesse em baixas concentrações. Para a etapa de validação do método foram realizados diversos ataques com adições de padrão e testes com o uso de tiouréia e iodeto de potássio com ácido ascórbico em diferentes concentrações com o objetivo de minimizar possíveis interferências presentes na matriz. Os resultados finais foram obtidos através da solubilização de materiais de referência internacionais geológicos na determinação de arsênio, bismuto e antimônio e se mostraram satisfatórios. / In this study, the steps for the development of a methodology to the determination of arsenic, antimony and bismuth in geological materials, with the use of hydride generation and ICPOES are being described. The methodology is sensitive due to that, subject is bound to suffer interferences from matrix elements. Optimizations in operations and analyticals parameters were done in the equipment. They aimed a better sensitivite and an efficient method of complete dissolution techniques in a sample of rock, which permits the determination of the analyte in low concentrations. For the steps of methodology validation, many dissolutions were realized with the addition of standard and tests with the use of thiourea and KI and acid ascorbic in different concentrations with the objective of minimizing some interferences from matrix elements. The final results were obtained through dissolutions with international reference materials in the determination of arsenic, antimony and bismuth.

Submitted by Biblioteca de Pós-Graduação em Geoquímica BGQ (bgq@ndc.uff.br) on 2018-02-28T17:03:22Z No. of bitstreams: 1 Dissertação de Watson Lopes.pdf: 460692 bytes, checksum: 84daa08fc121a4dab8c57c36f24c8b2d (MD5) / Made available in DSpace on 2018-02-28T17:03:23Z (GMT). No. of bitstreams: 1 Dissertação de Watson Lopes.pdf: 460692 bytes, checksum: 84daa08fc121a4dab8c57c36f24c8b2d (MD5) / Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Universidade Federal Fluminense. Instituto de Química. Programa de Pós-Graduação em Geoquímica, Niterói, RJ / Neste trabalho, foram desenvolvidos procedimentos analíticos para a determinação das concentrações biodisponíveis de arsênio e selênio em sedimentos por espectrometria de emissão ótica com fonte de plasma indutivamente acoplado, utilizando o método de geração de hidretos com o CMA (analisador concomitante de metais) e a metodologia recomendada pela US EPA (Agência de Proteção Ambiental dos Estados Unidos) para o preparo das amostras pelo método 3051. O CMA é um gerador de hidretos usado para determinar, concomitantemente, o maior número de elementos (formadores e não formadores de hidretos), em uma única análise. Ele consiste em um sistema com nebulizador pneumático e uma câmara ciclônica especial, capaz de transportar os elementos formadores e os não formadores de hidretos, simultaneamente, sem perda de sensibilidade. As condições experimentais foram otimizadas para se obter a melhor performance de operação do CMA como gerador de hidretos. Dentre estas condições podemos citar: vazão do gás do plasma, vazão do “gás de envoltório”, vazão da amostra, vazão da solução de NaBH4, vazão da solução do ácido clorídrico, concentrações de NaBH4 e do ácido e pressão do gás de nebulização. Para minimizar as interferências produzidas pelos íons de metais de transição (Cd2+, Co2+, Cu2+, Fe3+ e Ni2+) na determinação de arsênio e selênio foi utilizada alta concentração de HCl para a geração de hidretos e a validação do método foi obtida através da análise de uma amostra de referência certificada ( lama industrial NIST-SRM 2782) e de uma amostra com valor informado ( sedimento NIST-SRM 8704). / An analytical procedure was developed in this work for the determination of bioavailable concentrations of arsenic and selenium in sediment samples by inductively coupled plasma optical emission spectrometry using hydride generation, employing a concomitant metal analyzer (CMA) and the US EPA (Environmental Protection Agency from USA) 3051 method for sample preparation. The CMA is a hydride generator that can be used to determine hydride and nonhydride forming elements in a single run. This system consists of a pneumatic nebulizer coupled to a special cyclonic chamber, in which the aerosol containing both hydride forming and non-forming elements are transported towards the ICP torch and the measurements can be done without sensitivity losses. The experimental conditions were optimized in order to obtain best CMA operational performance as a hydride generator. Several variables were studied such as: plasma gas, sheath gas, sample, sodium borohydride, hydrochloric acid flow rates as well as borohydride and hydrochloric acid concentrations and nebulization pressure. For minimization of interference due to transition metal ions (Cd2+, Co2+, Cu2+, Fe3+ and Ni2+) to the arsenic and selenium signals, a higher hydrochloric acid concentration was used for the hydride generation, and the procedure was validated by the analysis of certified reference material (NIST-SRM 2782 industrial sludge) and reference material (NIST-SRM 8704 sediment).