Journal of Food, Agriculture and Environment

Spectrophotometric quantification of ascorbic acid contents of fruit and vegetables using the 2,4 dinitrophenylhydrazine method

Author(s):

Majeed Al-Ani ^1*, Linus U. Opara ², Dalila Al-Bahri ¹, Nadia Al-Rahbi ¹

Recieved Date: 2007-04-11, Accepted Date: 2007-07-27

Abstract:

Accurate quantification of the nutritional and antioxidant properties of raw materials is important in the diet and nutritional management. In this study, the 2,4-dinitrophenylhydrazine colorimetric method widely used for determination of ascorbic acid level in biological fluids was adapted to estimate total vitamin C content in fruits. The procedure depends on the principle of oxidation of L-ascorbic acid to dehydroascorbic acid and 2,3- diketo-gulonic acid, followed by reaction with 2,4-dinitrophenylhydrazine. After treatment with sulfuric acid, a colored product is formed which is absorbed at 520 nm. Using standard ascorbic acid at different concentrations, Beer’s law was obeyed up to 2.0 mg dL^-1 concentration range, which resulted in the following equation of the linear calibration curve: y = 4.0827x – 0.0423, R² = 0.9923. The most critical and decisive step in the procedure for an accurate reading is the preparation of a final clear extract of the fruit or vegetable. Analysis of vitamin C contents in selected fruit using both titrimetric and spectrophotometric methods are presented.

Keywords:

Ascorbic acid, total vitamin C, 2,4-dinitrophenylhydrazine, spectrophotometric method, fruit and vegetables

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Journal: Journal of Food, Agriculture and Environment
Year: 2007
Volume: 5
Issue: 3&4
Category: Food and Health
Pages: 165-168

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