| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1986: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1985: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
Generally, 2, 4 dinitrophenyl hydrazine (DNP) method is employed as a standard method for the determination of vitamin C in foods. However, the operation procedures of this method are rather complicated and time consuming, so a more convenient and rapid determination method is necessary. It is well known that ascorbic acid oxidase specifically catalyzes the oxidation reaction of ascorbic acid (AsA) to dehydroascorbic acid (DAsA). In this study, we used a biosensor and determined AsA by the estimation of the decreasing amount of dissolved oxygen (DO) in the solution consumed during the reaction. We established a method for the determination of total vitamin C by using dithiothreitol as reducing agent for the DAsA reduction. The optimum analysis conditions for the determination of AsA and reduction conditions of DAsA were established by estimating the consumption of DO during reaction. The two determination methods, the standard method and the sensitive one for high and low AsA concentration samples respectively, were established. A linear relationship was found between the DO uptake and AsA DAsA concentrations. AsA and DAsA concentrations were twice the DO uptake, thus this method makes it possible to determine AsA and DAsA without using a calibration curve. It was found that the determination level of AsA and DAsA as low as 0.01mM is possible using this biosensor system. The values of AsA contents in the juice obtained using the present method have a good comparability to those obtained by DNP and HPLC method. The procedure for this analytical method was quite simple and applicable for small amount samples. Due to the specificity of the enzyme used, it was possible to determine vitamin C accurately. This method is applicable for a rapid determination of total vitamin C contents in foods.
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