Extra??o de ?cidos ?rico e asc?rbico utilizando novos sistemas aquosos bif?sicos com posterior detec??o eletroqu?mica

Autor: Gon?alves, Laryssa Fernanda da Silva
Přispěvatelé: Lemos, Leandro Rodrigues de, Franco, D?bora Vilela, Carvalho, Mohana Zorkot, Senra, Tonimar Domiciano Arrighi, Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM)
Jazyk: portugalština
Rok vydání: 2019
Předmět:
Zdroj: Repositório Institucional da UFVJM
Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM)
instacron:UFVJM
Popis: Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2020-10-08T20:10:06Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) laryssa_fernanda_silva_goncalves.pdf: 2278218 bytes, checksum: 0c024f4034cc71e51536b88f741e0215 (MD5) Approved for entry into archive by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2020-10-09T18:09:19Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) laryssa_fernanda_silva_goncalves.pdf: 2278218 bytes, checksum: 0c024f4034cc71e51536b88f741e0215 (MD5) Made available in DSpace on 2020-10-09T18:09:19Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) laryssa_fernanda_silva_goncalves.pdf: 2278218 bytes, checksum: 0c024f4034cc71e51536b88f741e0215 (MD5) Previous issue date: 2019 As metodologias anal?ticas baseadas em t?cnicas eletroqu?micas (TE) s?o simples, r?pidas e de baixo custo para detec??o de diferentes analitos. Entretanto, em an?lise de matrizes biol?gicas, devido ? complexidade das amostras, podem ocorrer interfer?ncias pela presen?a de compostos eletroativos, como o ?cido ?rico (AU) e o ?cido Ascorbico (AA), sendo necess?ria a etapa pr?via de clean-up. Neste sentido, os sistemas aquosos bif?sicos (SAB) v?m sendo estudados como alternativa promissora ? extra??o l?quido?l?quido tradicional pelas diversas vantagens que o mesmo possui, como a utiliza??o de reagentes n?o-t?xicos e n?o-inflam?veis, o baixo custo e a r?pida separa??o de fases. O presente trabalho objetivou a obten??o de dados de equil?brio l?quido-l?quido para novos SAB, formados por L64 ou F68 ou PEG400 + sais de sulfato + ?gua e a caracteriza??o de tais sistemas. Al?m disso, estudou-se o comportamento eletroqu?mico dos sistemas e a parti??o dos ?cidos ?rico e asc?rbico, avaliando a intera??o destes com as fases do sistema, visto que o acoplamento das t?cnicas eletroqu?micas com o SAB ainda n?o foi estudado. Para os sistemas compostos por copol?meros tribloco + sais de sulfato avaliou-se a influ?ncia da temperatura, dos eletr?litos e da massa molar dos pol?meros, al?m de seu comportamento eletroqu?mico. Observou-se que a capacidade dos eletr?litos em promover a separa??o de fase foi melhor para CuSO4 que para o Fe2(SO4)3 e que o copol?mero F68 ? mais eficiente para induzir a separa??o de fases do que o L64. Com rela??o ? avalia??o eletroqu?mica, observou-se que os sistemas n?o possuem boa resposta, visto que os sais de cobre e ferro interferem fortemente na resposta do analito. J? para os sistemas formados por PEG 400 + Li2SO4 + ?gua foram estudados a influ?ncia da temperatura e do pH no sistema e a influ?ncia destes par?metros na parti??o dos UA e AA. Avaliou-se, al?m disso, a detec??o dos analitos atrav?s de t?cnicas eletroqu?micas. Concluiu-se que para estes sistemas as influ?ncias da temperatura e do pH n?o foram pronunciadas na curva binodal, mostrando que a separa??o de fases foi um processo endot?rmico sendo dirigido termodinamicamente pela entropia. Com rela??o ? parti??o do AU e do AA no sistema, observou-se que ambos os analitos possuem maior afinidade pela fase superior (FS) e que, tanto a temperatura como o pH influenciam fortemente na parti??o destes. Os dados eletroqu?micos corroboraram com os resultados obtidos nas an?lises espectofotom?tricas, mostrando a tend?ncia do AU em particionar para a FS e do AA para a FI. Portanto, este trabalho demostrou a potencialidade do acoplamento das TE com os SAB expandindo a gama de aplica??es de ambas as t?cnicas. Tese (Doutorado) ? Programa de P?s-Gradua??o Multic?ntrico em Qu?mica de Minas Gerais, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2019. Analytical methodologies based on electrochemical techniques (ET) are simple, fast and low cost methods to detect different analytes. However, in the analysis of biological matrices, because of the complexity of the samples, interference may occur due to the presence of electroactive compounds, such as Uric Acid (UA) and Ascorbic Acid (AA), requiring the previous clean-up step. In this context, the Aqueous Two-Phases Systems (ATPS) have been studied currently as a promising alternative to traditional liquid-liquid extraction for the various advantages that it has, such as the use of non-toxic and non-flammable reagents, low cost and fast phase separation. The present work aims to obtain liquid-liquid equilibrium data for new ATPS, formed by L64 or F68 or PEG400 + sulfate salts + water and characterize these systems. Moreover, aims to study the electrochemical behavior of the systems and partition of uric and ascorbic acids, evaluating the interaction of these with the phases of the system, whereas the coupling of the electrochemical techniques with ATPS has not been studied yet. For compound systems by triblock + sulfate salts the influence of temperature, electrolytes and molar mass of the polymers, as well as their electrochemical behavior, were evaluated. It was observed that the ability of the electrolytes to promote phase separation was better for CuSO4 than for Fe2(SO4)3 and that the F68 copolymer is more efficient at inducing phase separation than L64. Concerning the electrochemical evaluation, it was observed that the systems do not have a good response, since the sulphate salts strongly interfere in the analyte response. For the systems formed by PEG400 + Li2SO4 + water, the influence of temperature and pH on the system and the influence of these parameters on the partition of uric and ascorbic acid were studied. In addition, the detection of the analytes by electrochemical techniques was evaluated. It was concluded that for this system the influences of temperature and pH were?nt pronounced in the binodal curve, that is the phase separation was an endothermic process directed thermodynamically by the entropy. Regarding to the partition of AU and AA in the system, it was observed that both analytes have higher affinity for TP and that both temperature as the pH strongly influence the partitioning of these. The electrochemical data corroborated with the results obtained in the spectrophotometric analysis, showing the tendency of the AU to partition for the TP and the AA for the BP. Therefore, this work demonstrated the potential of the coupling of the electrochemical techniques with ATPS, expanding a range of possible applications.
Databáze: OpenAIRE
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