Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-27T13:40:49Z No. of bitstreams: 5 ana.pdf: 1542449 bytes, checksum: 6abec3dbd7b8c5cd7aec1cd8cc44d636 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-27T18:10:12Z (GMT) No. of bitstreams: 5 ana.pdf: 1542449 bytes, checksum: 6abec3dbd7b8c5cd7aec1cd8cc44d636 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) / Made available in DSpace on 2015-02-27T18:10:13Z (GMT). No. of bitstreams: 5 ana.pdf: 1542449 bytes, checksum: 6abec3dbd7b8c5cd7aec1cd8cc44d636 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) Previous issue date: 2013-02-21 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (Capes) / Funda??o de Amparo ? Pesquisa do estado de Minas Gerais (FAPEMIG) / O presente trabalho descreve o desenvolvimento de um sensor voltam?trico altamente seletivo e sens?vel para dopamina (DA), ?cido asc?rbico (AA) e ?cido ?rico (AU) utilizando um eletrodo de grafite pirol?tico de plano basal modificado com 1,4-naftoquinona adsorvida sobre nanotubos de carbono de paredes m?ltiplas (EGPPB/NTCPM/NQ). Imagens de Microscopia Eletr?nica de Varredura foram utilizadas para caracterizar os materiais. Os processos de oxida??o de DA, AA e AU foram investigados por Voltametria C?clica (VC) e Voltametria de Pulso Diferencial (VPD). O eletrodo modificado apresentou excelente atividade catal?tica para oxida??o de DA, AA e AU, fornecendo tr?s picos voltam?tricos bem definidos em aproximadamente ? 0,050, 0,145 e 0,270 V vs. Ag/AgCl, respectivamente, por VPD. Ap?s a otimiza??o dos par?metros experimentais (solu??o 0,1 mol L-1 de tamp?o fosfato pH 7,5), obteve-se as curvas anal?ticas para DA, AA e AU, cujas faixas de linearidade foram 10,0-70,0 nmol L-1, 40,0-280,0 ?mol L-1 e 2,0-14,0 ?mol L-1, respectivamente. Os limites de detec??o e sensibilidade foram, respectivamente, 0,126 nmol L-1 e 0,653 ?A/ nmol L-1 para DA, 2,136 ?mol L-1 e 0,076 ?A/ ?mol L-1 para AA e 0,018 ?mol L-1 e 9,888 ?A/ ?mol L-1 para AU. O sensor foi aplicado com sucesso em amostras de urina humana e os resultados mostraram que o mesmo n?o sofre interfer?ncia da matriz biol?gica. Estudos de adi??o e recupera??o dos analitos foram realizados para avaliar a exatid?o do m?todo e obteve-se uma porcentagem de recupera??o entre 95,14% e 101,49% para DA, 96,10% e 103,47% para AA e 97,90% e 102,32% para AU. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2012. / The present work describes the development of a highly selective and sensitive voltammetric sensor for dopamine (DA), ascorbic acid (AA) and uric acid (AU) using a basal plane pyrolytic graphite electrode modified with 1,4-naphthoquinone adsorbed on multi-walled carbon nanotubes (EGPPB/NTCPM/NQ). Images of Scanning Electron Microscopy were used to characterize the materials. Oxidation process of DA, AA and AU were investigated by Cyclic Voltammetry (VC) and Differential Pulse Voltammetry (VPD). The modified electrode showed an excellent catalytic activity towards the oxidations of DA, AA and AU, providing three well-defined voltammetric peaks at ? 0.050, 0.145 e 0.270 V vs. Ag/AgCl, respectively, by VPD. After optimization of experimental parameters (0.1 mol L-1 phosphate buffer solution pH 7.5), the calibration plots were obtained for DA, AA and AU, in the range from 10.0 up to 70.0 nmol L-1, 40.0 up to 280.0 ?mol L-1 and 2.0 up to 14.0 ?mol L-1, respectively. The detection limit and sensitivity were, respectively, 0.126 nmol L-1 and 0.653 ?A/ nmol L-1 for DA, 2.136 ?mol L-1 and 0.076 ?A/ ?mol L-1 for AA and 0.018 ?mol L-1 and 9.888 ?A/ ?mol L-1 for AU. The sensor developed has been successfully applied in human urine samples and the results showed that the matrix biological does not affect the response of the sensor. Studies of addition and recovery for DA, AA and AU were carried out to evaluate the error of the method and was verified a recovery percentage between 95.14% and 101.49% for DA, 96.10% and 103.47% for AA and 97.90% and 102.32% for AU.

Made available in DSpace on 2014-12-17T14:08:43Z (GMT). No. of bitstreams: 1 MariaSMQ_DISSERT_1-36.pdf: 5283210 bytes, checksum: e75f1aa1d6f8e40607338226667f1b0d (MD5) Previous issue date: 2011-02-07 / Estuaries are environments prone to the input of chemical pollutants of various kinds and origins, including polycyclic aromatic hydrocarbons (PAHs). Anthropogenic PAHs may have two possible sources: pyrolytic (with four or more aromatic rings and low degree of alkylation) and petrogenic (with two and three aromatic rings and high degree of alkylation). This study aimed to evaluate the levels, distribution and possible sources of polycyclic aromatic hydrocarbons in the estuary of the Potengi river, Natal, Brazil. Samples of bottom sediments were collected in the final 12 km of the estuary until its mouth to the sea, where the urbanization of the Great Natal is more concentrated. Sampling was performed on 12 cross sections, with three stations each, totaling 36 samples, identified as T1 to T36. The non alkylated and alkylated PAHs were analyzed by gas chromatography coupled to mass spectrometry (GC / MS). PAHs were detected in all 36 stations with total concentration on each varying 174-109407 ng g-1. These values are comparable to those of several estuarine regions worldwide with high anthropogenic influence, suggesting the record of diffuse contamination installed in the estuary. PAHs profiles were similar for most stations. In 32 of the 36 stations, low molecular weight PAHs (with 2 and 3 ring: naphthalene, phenanthrene and their alkylated homologues) prevailed, which ranged from 54% to 100% of the total PAH, indicating that leaks, spills and combustion fuels are the dominant source of PAH pollution in the estuary. The level of contamination by PAHs in most stations suggests that there is potential risk of occasional adverse biological effects, but in some stations adverse impacts on the biota may occur frequently. The diagnostic ratios could differentiate sources of PAHs in sediments of the estuary, which were divided into three groups: petrogenic, pyrolytic and mixing of sources. The urban concentration of the Great Natal and the various industrial activities associated with it can be blamed as potential sources of PAHs in bottom sediments of the estuary studied. The data presented highlight the need to control the causes of existing pollution in the estuary / Os estu?rios s?o ambientes prop?cios ao aporte de poluentes qu?micos de diversas naturezas e origens, incluindo Hidrocarbonetos Polic?clicos Arom?ticos (HPA). Os HPA antr?picos s?o de duas fontes poss?veis: pirol?tica (com quatro ou mais an?is arom?ticos e baixo grau de alquila??o) e petrog?nica (com dois e tr?s an?is arom?ticos e alto grau de alquila??o). O presente trabalho teve como objetivo avaliar os n?veis, distribui??o e poss?veis fontes de Hidrocarbonetos Polic?clicos Arom?ticos no estu?rio do rio Potengi, Natal-RN. Amostras de sedimentos de fundo foram coletadas nos 12 km finais do estu?rio at? a sua foz, onde a urbaniza??o da Grande Natal ? mais concentrada. A amostragem foi realizada em 12 se??es transversais, com tr?s esta??es em cada uma, totalizando 36 amostras, identificadas de T1 a T36. Os HPA alquilados e n?o alquilados foram analisados por cromatografia gasosa acoplada a um detector seletivo de massas (CG/EM). Foram detectados HPA em todas as 36 esta??es, com concentra??o total em cada uma variando de 174 a 109407 ng g-1. Esses valores s?o compar?veis aos de v?rias regi?es estuarinas mundiais com grande influ?ncia antr?pica, o que sugere o registro de contamina??es difusas instaladas no estu?rio. O perfil de HPA foi similar para a maioria das esta??es. Em 32 das 36 esta??es predominaram HPA de baixo peso molecular (com 2 e 3 an?is: naftaleno, fenantreno e seus hom?logos alquilados), que variaram de 54% a 100% em rela??o ao total de HPA, indicando que vazamentos, derramamentos e queima de combust?veis s?o a fonte dominante de polui??o por HPA no estu?rio. O n?vel de contamina??o por HPA na maioria das esta??es sugere que h? risco potencial de ocasionais efeitos biol?gicos adversos serem observados, por?m em algumas esta??es se confirmam que impactos adversos sobre a biota ocorrem com freq??ncia. As raz?es diagn?sticas permitiram diferenciar as fontes de HPA nos sedimentos do estu?rio, que foram divididos em tr?s grupos: sedimentos com padr?es de introdu??o de hidrocarbonetos petrog?nicos, pirol?ticos e de mistura de fontes. A concentra??o urbana da Grande Natal e as atividades industriais diversas a ela associadas podem ser responsabilizadas como fontes potenciais dos HPA nos sedimentos de fundo do estu?rio estudado. Os dados apresentados evidenciam a necessidade de se controlar as causas da polui??o existente no estu?rio

Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-19T13:34:45Z No. of bitstreams: 5 fer.pdf: 3531496 bytes, checksum: da51c0e714843d62cd73ad67737d85b2 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-02-20T10:58:08Z (GMT) No. of bitstreams: 5 fer.pdf: 3531496 bytes, checksum: da51c0e714843d62cd73ad67737d85b2 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) / Made available in DSpace on 2015-02-20T10:58:09Z (GMT). No. of bitstreams: 5 fer.pdf: 3531496 bytes, checksum: da51c0e714843d62cd73ad67737d85b2 (MD5) license_url: 52 bytes, checksum: 3d480ae6c91e310daba2020f8787d6f9 (MD5) license_text: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) license.txt: 2110 bytes, checksum: b4c884761e4c6c296ab2179d378436d4 (MD5) Previous issue date: 2013-02-20 / L-Dopa ? convertida em dopamina no c?rebro e continua a ser a droga mais amplamente prescrita no tratamento da doen?a de Parkinson. Um sens?vel e seletivo sensor foi desenvolvido para a determina??o voltam?trica de L-Dopa em formula??es farmac?uticas usando um Eletrodo de Grafite Pirol?tico de Plano Basal (EGPPB) modificado com cloro(piridil)bis(dimetilglioximato) de cobalto (III) (Co(DMG)2ClPy), um modelo sint?tico da vitamina B12, adsorvido em Nanotubos de Carbono de Paredes M?ltiplas (NCPM), o qual foi denominado EGPPB/NCPM/Co(DMG)2ClPy. Microscopia Eletr?nica de Varredura e Espectroscopia no Infravermelho por Transformada de Fourier foram utilizadas para caracterizar os materiais. A oxida??o de L-Dopa utilizando o EGPPB/NCPM/Co(DMG)2ClPy foi investigada por Voltametria C?clica, Amperometria, Voltametria de Pulso Diferencial e Voltametria de Onda Quadrada. O eletrodo modificado apresentou uma excelente atividade catal?tica para a oxida??o de L-Dopa em 180 mV vs. Ag/AgCl. Os par?metros que influenciam a resposta do eletrodo foram investigados. As condi??es ?timas foram encontradas para o eletrodo modificado com 100 ?mol L-1 de Co(DMG)2ClPy, 2 mg mL-1 de NCPM, em solu??o tamp?o fosfato na concentra??o de 0,2 mol L-1 (pH 7,4). O n?mero de el?trons envolvidos na oxida??o de L-Dopa foi igual a dois. As correntes de pico voltam?tricas apresentaram uma resposta linear para a concentra??o de L-Dopa no intervalo de 3 a 100 ?mol L-1 para n = 12 (R = 0,9992), com sensibilidade, limite de detec??o e limite de quantifica??o iguais a 4,43 ?A cm-2/?mol L-1, 0,86 e 2,87 ?mol L-1, respectivamente. O Desvio Padr?o Relativo para 10 determina??es de solu??o 50 ?mol L-1 de L-Dopa foi de 1,63%. Os resultados obtidos para a determina??o de L-Dopa em formula??es farmac?uticas est?o de acordo com o m?todo de compara??o oficial. Estudos de adi??o e recupera??o do analito foram realizados para avaliar a exatid?o do m?todo e verificou-se que foi poss?vel uma porcentagem de recupera??o entre 99,4 e 101,5% para a L-Dopa. Portanto, o sensor desenvolvido pode ser aplicado com sucesso para a determina??o do referido f?rmaco em medicamentos. / Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2011. / ABSTRACT L-Dopa is converted to dopamine in the brain and remains the most widely prescribed drug in the treatment of Parkinson's disease. A sensitive and selective method was developed for the voltammetric determination of L-Dopa in pharmaceutical formulations using a Basal Plane Pyrolytic Graphite Electrode (BPPGE) modified with chloro(pyridil)bis(dimethylglyoximato)cobalt(III) (Co(DMG)2ClPy), synthetic model of vitamin B12, absorbed on Multi-walled Carbon Nanotube (MWCNT), denominated MWCNT/Co(DMG)2ClPy/BPPGE. Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy were used to characterize the materials. The oxidation of L-Dopa using the MWCNT/Co(DMG)2ClPy/BPPGE was investigated by Cyclic Voltammetry, Amperometry, Differential Pulse Voltammetry and Square Wave Voltammetry. The modified electrode showed an excellent catalytic activity for L-Dopa oxidation at 180 mV vs. Ag/AgCl. The parameters that influence on the electrode response were investigated. The optimum conditions were found to the modified electrode with 100 ?mol L-1 Co(DMG)2ClPy, 2 mg mL-1 MWCNT, in 0.2 mol L-1 phosphate buffer solution (pH 7.4). The number of electrons involved in L-Dopa oxidation was two. Voltammetric peak currents showed a linear response for L-Dopa concentration in the range from 3 up to 100 ?mol L-1 for n = 12 (R = 0.9992), with a sensitivity, detection limit and quantification limit of 4.43 ?A cm-2/?mol L-1, 0.86 and 2.87 ?mol L-1, respectively. The Relative Standard Deviation for 10 determinations of 50 ?mol L-1 L-Dopa was 1.63%. The results obtained for L-Dopa determination in pharmaceutical formulations was in accordance with the official method of comparison. Studies of addition and recovery of the analyte were carried out to evaluate the error of the method and was verified a recovery percentage between 99.4 and 101.5% for L-Dopa. Therefore the sensor developed can be applied successfully to the determination of this drug in pharmaceuticals formulations.