Abstract

SENSITIVE SPECTROPHOTOMETRIC DETERMINATION OF VITAMIN C IN HERBAL PRODUCTS AND PLANT SAMPLES.

Dr. Pooja V. Jagasia*

Abstract

A Simple, sensitive and accurate spectrophotometric method has been developed for determination of Vitamin C in synthetic mixtures and real samples. This method is based on the oxidation of Vitamin C by Known excess of Te(IV) in hydrochloric acid medium. The unreacted Te(IV) reacts with iodide in the same acid medium to liberate iodine, which then reacts with starch to yield a blue coloured starch-iodine complex, which shows maximum absorbance at 480 nm. The reacted oxidant corresponds to vitamin C content. This reaction system is the basis for the indirect spectrophotometric determination of vitamin C. vitamin C when added in increasing amounts, consume Te(IV) and decreases the concentration of Te(IV). The absorbance is found to decrease linearly with increase in concentration of vitamin C. A 1.0 mL of 2.0 mol L–1 concentrationof HCl was found to be optimum for the oxidation of vitamin C within 10 min, and hence the same concentration was employed for the determination. The volumes of 1.5 mL of 0.5% KI and 1.0 mL of 0.5 % starch solution in a total volume of 10 mL of reaction mixture were found to be suitable for the analysis. The Beer’s range is obeyed in the concentration range of 0.2- 4.0ug/cm3. The molar absorptivity ans Sandell’s sensitivity values are found to be 0.0745 L mol-1cm-2 and 0.0197 μg cm-2 respectively. The cofficient of co-relation is found to be 0.967. The Regression equation is Y=0.18X +0.197. The method is successfully applied for the determination of vitamin C in orange peel powder,Mint leaves and spinach.

Keywords: Vitamin C, Tellerium, Herbal samples, plant material, spectrophotometer.