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  Home > JCE Print > Journal of Chemical Education > Issues > 2004  > October  >
In the Laboratory
Studying Current–Potential Curves Using Bipotentiometric Iodometric Back-Titration for the Determination of Ascorbic Acid in Fruits and Vegetables
Roxana A. Verdini and Claudia M. Lagier
Departamento de Química Analítica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, 2000, Rosario, Argentina
Cover
October 2004
Vol. 81 No. 10
p. 1482
Abstract
A method for the determination of the ascorbic acid content in fruits and vegetables was used to introduce the principles of voltammetry. The procedure combines an iodometric back-titration with voltammetric (bipotentiometric) end point detection, which minimizes the risk of ascorbic acid oxidation, allowing for a rapid and efficient quantification of vitamin C in fruits and vegetables. A better understanding of the titration curve is achieved by analyzing the schematic current–potential curves of the anodic and cathodic half-cell reactions during the titration. Hence, not only theoretical principles of voltammetry are considered, but also the applications of these techniques to quantify a chemical species in a complex matrix. As a result, the laboratory experiment proposed is a valuable tool for analytical chemistry students to discuss electrochemistry techniques in the context of an interesting application.
Supplement
Instructions for the students and notes for the instructor are available.
*  Contents JCE2004p1482W.doc (Microsoft Word)
 
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More Information
*  Citation
 Verdini, Roxana A.; Lagier, Claudia M. J. Chem. Educ. 2004 81 1482.
*  Keywords
 Analytical Chemistry; Consumer Chemistry; Electrochemistry; Food Science; Instrumental Methods; Laboratory Instruction; Redox Reactions; Titration / Titrimetry; Vitamins
*  History
 Created:
Last Updated:		 August 31, 2004
September 8, 2004
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