Determination of Vitamin C Content in Fruits and Vegetables by Using Indophenol Method, Ultraviolet-Visible Spectroscopy and High-Performance Liquid Chromatography

Yap, Yee Jie (2019) Determination of Vitamin C Content in Fruits and Vegetables by Using Indophenol Method, Ultraviolet-Visible Spectroscopy and High-Performance Liquid Chromatography. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

There were 3 method used for determining ascorbic acid content in lime, cabbage and yellow pepper which including Indophenol method, UV-Vis spectroscopy and HPLC. The equations for these methods were studied to calculate the concentration of ascorbic acid in fruits and vegetables samples. The Indophenol method shows that the yellow pepper sample has the highest vitamin C concentration among cabbage and lime which is 9.65 mg/mL. The results from UV-Vis Spectrophotometer are in a good agreement where the maximum absorption wavelength (λmax) for the ascorbic acid of prepared fruit samples and KMnO4 solution (100 μg/mL) occurred at 285 nm against the blank. The equation of the calibration graph was y = 0.004 x + 0.0013 (where y represents absorbance and x represents concentration of the series dilution, as μg/mL, R2 = 0.9462). Beer-Lambert equation was applied to determine the vitamin C concentration. Two methods were used to calculate HPLC results. The first method is to set up a ratio by using one of the series dilution concentration and the respective peak area and putting it equal to an unknown concentration, but known ascorbic acid peak area whereas the second method is using the equation of calibration curve equation (y = 0.0084x + 0.0965 where x is peak area and y is the concentration of the series of dilutions, as μg/mL, R² = 0.0738). Both instrumental methods results are compared and UV-Vis spectroscopy method is preferred in this study.