Abstract

NEW ANALYTICAL METHOD OF ASCORBIC ACID BY ITS REACTION WITH FREE RADICALS GENERATED FROM ZERO VALENT IRON IN AQUEOUS SOLTIONS

Jamil Rima*

ABSTRACT

Free radicals generated by ZVI (zero valent iron) was used for the determination of ascorbic acid in natural media. This method is based on the oxidation reaction between ascorbic acid and zero-valent iron powder and followed by the 2-thiobarbituric acid test. The by-products obtained from its reaction with ZVI and TBA give a visible absorption spectrum specific for ascorbic acid which shows two maximums at 450 nm and 535 nm. Ascorbic acid determined in fruit juice in order apply the method in natural media. The comparison of ascorbic acid concentrations determined by the new method and by the standard method and the labeled values in fruit juices and food supplements shows the acceptability of the new method . The values obtained by the new and the standard methods are to close .The linear dynamic range (mM) is between 0.05 and 2. Limit of detection (mM) is 0.01 and the Relative Standard d Deviation is 2%

Keywords: Ascorbic acid; spectrophotometer; Quantification; Internal standard addition method; reaction of free radicals with AA. iron powder