Desenvolvimento de sensores baseados em nanotubos de carbono para a determinação de hormônios em água do mar

• Ano de defesa: 2017
• Autor(a) principal: Okina, Renato Hisashi [UNIFESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paulo
• Palavras-chave em Português: Electrochemistry; Electroanalytical; Sensors; Carbon nanotubes; Strogens; Eletroquímica; Eletroanalítica; Sensores; Nanotubos de carbono; Estrógenos
• Link de acesso: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=5533684; http://repositorio.unifesp.br/handle/11600/50030

This work aimed de development of a glassy carbon sensor modified with multi-walled carbon nanotubes for determination of estrone, estriol and 17 α ethinylestradiol in seawater. Using the cyclic voltammetry technique it was possible to observe that the three hormones in study showed voltamograms typical of irreversible process in BR buffer 0.1 mol L-1, pH 7.0. The oxidation potential peak were 0.59 V, 0.57V e 0.56 V, for estrone, estriol and 17-α-ethinylestradiol, respectively. Also in cyclic voltammetry the study of pH of the medium and sweep velocity effect in the oxidation process for the three hormones were made, the results showed that the oxidation process is proton dependent and controlled by adsorption. The electrode modification method with successive addictions of carbon nanotubes showed efficiency for a better electrode surface cover, increasing the peak signal intensity of the three hormones and a bigger surface passivation resistance. The square wave voltyammetry parameters were optimized to the analytical method development, square wave amplitude, frequency and scan increment were optimized. After the parameters optimization the analytical curves were obtained for the three hormones, the results presented linearity in the concentration range 1.0x10-6 mol L-1 to 9.0x10-6 mol L-1 for estrone and estriol, and 1.0x10-6 mol L-1 to 4.5 x 10-6 mol L-1 for 17-α-ethinylestradiol. The recovery test for estrone in seawater sample showed the value of 74% for spiked sample at the concentration of 1.0 x 10-6, indicating the applicability of the developed methodology to quantify estrone directly in sea water.