Trabalhos Acadêmicos e Técnicos

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Navegando Trabalhos Acadêmicos e Técnicos por Assunto "4-nitroaniline"

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    Determinação de ácido ascórbico: um sensor eletroquímico à base de pasta de carbono com 4-nitroanilina adsorvida em silica gel modificada
    (Instituto Federal de Educação Ciência e Tecnologia de Alagoas, 2019-12-05) Santos, Monik Tamíres Silva; Cavalcante, Sarah Kelly Melo; http://lattes.cnpq.br/0820477133147241; Lima, Phabyanno Rodrigues; http://lattes.cnpq.br/9334426018309756; Cavalcante, Sarah Kelly Melo; http://lattes.cnpq.br/0820477133147241; Silva, Jailson dos Santos
    The present work describes the development of a multiple wall carbon nanotube paste electrode (MWCNTPE) based on 4-nitroaniline (4NA) adsorbed onto silica gel modified with zirconium oxide (SZ) to detect ascorbic acid (AA). The sensing surface was characterized by Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Infrared Spectroscopy (FTIR). The electroactive species, hydroxylamine / nitrous (R-NHOH / R-NO), was electrogenerated in situ from 4Nitroaniline after cycling in the potential range between 0.5 and -1.0 vs. Ag / AgCl in the first scan in 0.1 mol L-1 PBS buffer (pH 7.0) with a scanning rate of 0.02 Vs-1. The modified electrode showed efficient electrocatalytic activity against the oxidation of ascorbic acid in 0.3 V vs. Ag / AgCl. Electrochemical measurements including Cyclic Voltammetry (VC) and Chronoamperometry were used to study the behavior of the surface of the modified electrode used. These techniques were used to optimize the experimental parameters. Thus, under optimized conditions, the sensor presented a linear response range of 0.5 - 3.0 μmol.L-1, LD (0.15 μmol.L-1), LQ (0.48 μmol.L-1) and sensitivity of 7.60 (mA.L.mmol-1) adding to the sensor positive factors in sensitivity and selectivity. This sensor was applied for the amperometric determination of AA in food samples. The results were consistent with those obtained with the standard titration procedure.