Estudo da determinação de ácido ascórbico em solução utilizando eletrodo de carbono vítreo modificado com Nafion®
Nenhuma Miniatura disponível
Data
2017-03-28
Autores
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Federal de Goiás
Resumo
This work was developed with the objective of determining the oxidation profile of
ascorbic acid in solution using cyclic voltammetry, square wave voltammetry and
differential pulse voltammetry, observing the oxidation behavior due to the increase in
the concentration of ascorbic acid in solution using In the electrochemical
measurements, a carbon-modified glass-carbon electrode and Nafion®, a polymer
widely used in electrochemical analysis. The experiments had an emphasy on standard
ascorbic acid analysis, but were also performed with vitamin C tablets of different trade
marks, obtaining in both a significant increase of the anodic peak currents coming from
the oxidation of the ascorbic acid, resulting from a good stability Of the modified working
electrode. For comparison purposes with the Nafion®-modified glass carbon electrode,
standard ascorbic acid analyzes were also performed with the use of the vitreous carbon
electrode. With the results of the analysis it was possible to determine the mass of
ascorbic acid found in vitamin C tablets, from the construction of an analytical curve, in
which it presented the necessary parameters for this. By varying the scanning velocities
of the analyzes by cyclic voltammetry, it was possible to find out when plotting the
current x square root velocity graphs by which process the oxidation of ascorbic acid on
the electrode surface would occur. The electrochemical experiments with standard
ascorbic acid showed the oxidation behavior by varying the pH of the phosphate buffer
solution, evidencing the best pH range to work using the Nafion® modified glass carbon electrode. The use of square wave and differential pulse voltammetry techniques
allowed to now the profile of the oxidation of ascorbic acid in vitamin C tablets,
demonstrating a better sensibility in the peak current signal by the use of differential
pulse voltammetry.
Descrição
Citação
ARAÚJO, K. R. O Estudo da determinação de ácido ascórbico em solução utilizando eletrodo de carbono vítreo modificado com Nafion®. 2017. 75 f. Dissertação (Mestrado em Química) - Universidade Federal de Goiás, Goiânia, 2017.