Desenvolvimento de um sensor eletroquímico de carbono vítreo modificado com nanotubos de carbono e Náfion para determinação eletroanalítica do imidacloprido em amostras de água e melão

• Ano de defesa: 2018
• Autor(a) principal: Bruzaca, Evellin Enny Silva
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Imidacloprido; Nanotubos de carbono de paredes múltiplas; Voltametria de onda quadrada; Sensor eletroquímico
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/36398

In this work, an electrochemical sensor of glass carbon modified with multiple wall carbon nanotubes (fNTCPM) and Nafion® was developed for the determination of imidacloprid (IMI) in samples of melon and tap water using the technique of square wave voltammetry (SWV). From the studies carried out by cyclic voltammetry (CV) and SWV, it was observed that the process of IMI reduction is irreversible, with a load transfer coefficient (α) value equal to 0.141. Under optimized conditions (McIlvaine buffer pH 6, 0.50% Nafion®, Econd = -0.6 V, tcond. = 180 s, f = 10 s-1, a = 40 mV and ΔEs = 5 mV), calibration curves were constructed, presenting linearity in the concentration range of 1.99 × 10−7 mol L−1 to 1.77 × 10−6 mol L−1. The limits of detection (LD) and quantification (LQ) values were respectively 3.74 × 10−8 mol L−1 and 1.25 × 10−7. mol L−1. Repeatability and intermediate precision were evaluated and, in terms of relative standard deviation (RSD), the values obtained were 4.38% and 4.16%, respectively. To assess the accuracy of the proposed methodology, recovery trials on samples of melon and tap water were performed and the recovery rates obtained were compared with the rates obtained by high performance liquid chromatography (HPLC). The mean recovery rates obtained by VOQ for samples of melon and tap water were equal to 97.0% and 93.7%, respectively. The recovery rates obtained by HPLC for the same samples were 98.7% and 102.6%, respectively. By means of tests of significance, it was found that the average recovery rates for samples of melon and tap water obtained by VOQ are statistically equal to the average rates obtained by HPLC. Studies of the interference of inorganic and organic species in the proposed electroanalytical methodology were performed. These studies revealed that the species analyzed did not significantly interfere in the electrochemical response of IMI to the modified electrode. Thus, the electroanalytical methodology proposed in the present study is selective, sensitive and accurate in the determination of IMI in the analyzed samples and presents a performance similar to the standard methodology for determining IMI.