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KMID : 1160620010060020083
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Preventive Nutrition and Food Science
2001 Volume.6 No. 2 p.83 ~ p.86
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Effects of Fe(III) and Cu(II) Ions on the Autoxidation of L-Ascorbic Acid
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Kim Mi-Ok
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Abstract
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The autoxidation reaction of L-ascorbic acid (AsA), and, particularly, the oxidation rates of AsA in the presence of Fe(Ⅲ) or Cu(Ⅱ) ions were determined in water and methanol. UV spectral measurement (at 265 ㎚) and HPLC were used to determine the remaining amounts of AsA in water and methanol, respectively. It was found that, in the presence of metal ions, the autoxidation rate of AsA was significantly affected by the kinds of solvents used, and also by the kinds of metal ions present. Moreover, the first-order rate constants for the oxidation of non-dissociated AsA compared with dissociated-AsA were investigated. It was confirmed that the oxidation of AsA was more accelerated in the dissociated form of AsA than in the non-dissociated form of AsA in either with Fe(Ⅲ) or Cu(Ⅱ). It was also found that the Cu(Ⅱ) at a concentration of 0.1 μM had a more significant effect on the first-order rate constants for the autoxidation of AsA than Fe(Ⅲ) at 5 μM.
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KEYWORD
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L-ascorbic acid, autoxidation, Fe(III), Cu(II)
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