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Previous issue date: 2008-02-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In this work, the objective in study was the development of a biossensor potencyometric for urea detection, starting from the extracted urease of soy grains. Initially, was made a chemometrics study, through a planning factorial 24, objectified to find great conditions for the extraction of the urease without its properties were affected. Starting from this study, the best conditions were determined for the obtaining of rich extracts in urease, allowing the biossensors making with good characteristics. These were made using a platinum electrode as transducer with the dispersed urease in chitosan head office and reticulated in glutaraldehyde vapor. The biossensors obtained presented a limit of urea detection the same to 0,33 mM and lineal strip between 0,33 and 3 mM of the substratum. The time of answer was considered loud, mainly, in low concentrations of the substratum, where it was taken about 5 minutes by analysis. For high concentrations that time was reduced for not more than one minute. The time of life was limited by the adherence of the enzymatic membrane to the transducer, but it was possible to maintain the biossensor with operation for one month with about 50 accomplished measures. Application of the biossensor for analyses of fertilizers to the urea base presented excellent result for a sample with few interfering, but it was different when the used fertilizer was originating from of a complex sample. Even so the label was not expressed the text of nitrogen it was totally coming of the urea. An evaluation of the kinetic parameters of the catalytic reaction of the biossensor showed coherence with the results exposed in the literature / Neste trabalho, o alvo em estudo foi o desenvolvimento de um biossensor potenciom?trico para detec??o de ur?ia, a partir da urease extra?da de gr?os de soja. Inicialmente, fez-se um estudo quimiom?trico, atrav?s de um planejamento fatorial 24,
objetivando-se encontrar condi??es ?timas para a extra??o da urease sem que suas propriedades fossem afetadas. A partir deste estudo, determinaram-se as melhores condi??es para a obten??o de extratos ricos em urease, permitindo a confec??o de biossensores com boas caracter?sticas. Estes foram confeccionados usando um eletrodo de platina como transdutor com a urease dispersa em matriz de quitosana e reticulada em vapor de glutaralde?do. Os biossensores obtidos apresentaram um limite de detec??o de ur?ia igual a 0,33 mM e faixa linear entre 0,33 e 3 mM do substrato. O tempo de resposta foi considerado alto, principalmente, em concentra??es baixas do
substrato, onde se levou cerca de 5 minutos por an?lise. Para concentra??es altas esse tempo foi reduzido para pouco mais de um minuto. O tempo de vida foi limitado pela ader?ncia da membrana enzim?tica ao transdutor, mas foi poss?vel manter o
biossensor com funcionamento por um m?s com cerca de 50 medidas realizadas. A aplica??o do biossensor para an?lises de fertilizantes ? base de ur?ia apresentou excelente resultado para uma amostra com poucos interferentes, mas foi diferente
quando o fertilizante utilizado era oriundo de uma amostra complexa. Por?m o r?tulo n?o expressava se o teor de nitrog?nio era totalmente proveniente da ur?ia. Uma
avalia??o dos par?metros cin?ticos da rea??o catal?tica do biossensor mostrou coer?ncia com os resultados expostos na literatura
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/17587 |
| Date | 29 February 2008 |
| Creators | Oliveira, Katharina Carla Santos de |
| Contributors | CPF:50073788449, http://lattes.cnpq.br/7275955550556570, Hussein, Fabiana Roberta Gon?alves e Silva, CPF:64145557468, Farias, Robson Fernandes de, CPF:59668741404, http://lattes.cnpq.br/6868773742105583, Melo, Jailson Vieira de |
| Publisher | Universidade Federal do Rio Grande do Norte, Programa de P?s-Gradua??o em Qu?mica, UFRN, BR, F?sico-Qu?mica; Qu?mica |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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