Abstract:
Vitamin C or ascorbic acid is an important antioxidant for the human body, it is required to keep minerals in the reducing state, which enhances their absorption process. There are several methods for estimating ascorbic acid depends on the oxidation and reduction properties. This study was aimed to applying a simple, accurate and sensitive spectroscopic method for determination of vitamin C using potassium chromate-Diphenyl carbazide. The method is based on oxidizing ascorbic acid with a known excess amount of potassium chromate and then estimating the unreacted chromate using diphenyl carbazide and The method was applied to samples of pure ascorbic acid, orange juice. The iodine titration method was used as a reference method for comparison. The results of the study showed that the absorption and λmax remain constant at 548 nm in the strong acidic medium, and the standard calibration curve was linear up to a concentration of 5 x 10-4 M of ascorbic acid, and the correlation coefficient r = 0.9911 and molar absorptivity was 4.11X103 l mol-1 cm-1. Statistical analysis of practical data indicated that the method is accurate and presise and that there is no significant difference in accuracy between the tested method and the reference method and that there is no evidence of a significant difference between the two sets of results at 95% confidence interval The proposed method was successfully applied to estimating ascorbic acid in the analyzed samples and was accurate and selective .
