Keywords
humic acids
iron(III) ions
ascorbic acid
How to Cite
Abstract
An amperometric sensor was constructed, by using humic acids to immobilize Fe 3+ ions on a carbon paste electrode (CPE-HA-Fe), and used for ascorbic acid (H 2 A) determination. The cyclic voltammogram of the electrode showed electrochemical response due to the Fe 3+ /Fe 2+ couple at E 1/2 =+0.78 V vs SCE, using 0.5 mol L -1 KCl and 0.2 mol L -1 acetate/0.020 mol L -1 phosphate buffer, at pH = 5.4, as supporting electrolyte. When H 2 A is added to the electrolyte solution it is observed an oxidation process. The oxidation current, obtained by chronoamperommetry at +0.87 V vs SCE, is proportional to the concentration, represented by the equation I(μA) = 7.6286 [H 2 A] (mmol L -1 ) + 1.9583, r = 0.9996, for concentrations between 0.0 and 1.4 mmol L -1 . The electrode showed high stability and was used for H 2 A determination in a natural orange juice.
References
J. O. Pontólio, N. Ferranti, M. L. A. M. Campos, and J. R. [2]
Romero, J. Electroanal. Chem. 584 (2005) 124.
W. S. Cardoso, and Y. Gushikem, J. Electroanal. Chem. 583
(2005) 300.
M. M. Ardakani, Z. Akrami, H. Kazemian, and H. R. Zare, J.
Electroanal. Chem. 586(2006)31.
M. H. Pournaghi-Azar, and H. Nahalparvari, J. Electroanal.
Chem.583 (2005) 307.
X. Lin, C. Jiang, Anal. Sci. 22 (2006) 697.
F. J. Stevenson, Húmus Chemistry: Genesis, composition,
reactions, John Wiley & Sons, INC., New York, 2a ed., 1994.
J. C. Rocha, A. H. Rosa, Substâncias Húmicas Aquáticas, Inte-
ração com Espécies Metálicas, Ed. Unesp, São Paulo-SP, 2003.
R. S. Swift, in: Methods of Soil Analysis Part 3: Chemical
Methods (SSSA Book Series No.5.), Sparks, D.L. ed., SSSA and
ASA, Madison, WI, 1996.
M. O. O. Rezende, and F. N. Crespilho, Quim. Nova 27
(2004) 964.
W. T. L. Silva, C. Thobie-Gautier, M. O. O. Resende, and N.
El Murr, Electroanalysis 14 (2002) 71.
C. Wang, B. Zhu, and H. Li, Electroanalysis 11 (1999) 183.
C. Wang, H. Zhang, Y. Sun, and H. Li, Anal. Chim. Acta 361
(1998) 133.
Q. Y. Sun, C. M. Wang, L. X. Li, and H. L. Li, Fresenius J.
Anal. Chem. 363 (1999) 114.
Z. Navratilova, and P. Kula, Anal. Chim. Acta 273 (1993) 305.
C.D. García, and P.I. Ortiz, Talanta 61 (2003) 547.
M. J. Tedesco, C. Geanello, C. A. Bissani, H. E. Bohnen, and
S. A. J. Volkweiss, Análises de Solo, Plantas e Outros Materiais,
Departamento de Solos, Faculdade de Agronomia, Universidade
Federal do Rio Grande do Sul, Porto Alegre, RS, 1995.
IMESP, Normas Técnicas do Instituto Adolfo Lutz, São
Paulo, SP, Brasil, 1985.
G. Sposito, The Chemistry of Soils, Oxford University
Press, New York, 1989.
F. A. Cotton, G. Wilkinson, C. A. Murillo, and M.
Bochmann, Advanced Inorganic Chemistry, sixth ed., John
Willey & Sons, Inc., New York, 1999.
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