Development of Methods for the Determination of Vitamin C Content in some Dry Fruits and Leaves, Laloub and Mesquite

Abstract

In this study, vitamin C has been determined by iodine titration in which starch was used as indicator in which four solvents were used to extract vitamin C from fruits and leaves samples of Balanites aegyptiaca and Prosopis juliflora. When it was extracted in acetic acid it gave maximum percentage of vitamin C in Balanites aegyptiaca leaves, BL (54.7) and minimum percentage for BF (1.76). However, when it was extracted with a mixture of 0.3M metaphosphoric acid and 1.4M acetic acid, the highest percentage was in BF (71.39) and the lowest percentage (15.8) for Prosopis juliflora leaves, PL .In contrast, when the vitamin was extracted with a mixture of 4.5% metaphosphoric acid and 1% sulphuric acid, the results were 52.75% for BL and 7.07% for the Prosopis juliflora fruits (PF). HPLC was used with two percentages of extracting solution: first when the percentages of metaphosphoric acid were 2%, it gave highest value in PF fruits (16.128 ppm) followed by BL (7.727 ppm) and PL 5.597 ppm ,but the lowest value of the vitamin was found in BF (3.794 ppm). But when the percentage of metaphosphoric acid was 4.5% it gave highest value of vitamin C in BL (461.5 ppm), followed by BF (391ppm), while PL gave 315.1 ppm and PF gave the lowest value 216.5 ppm.The HPLC method was validated for linearity, ruggedness, inter –and intra precision and recovery A UV spectrophotometric method for the determination of cerium has been developed. In order to establish the optimum experimental conditions, the effect of various parameters comprising absorption, wavelength, temperature, reaction time after preparation and pH was investigated. It was found that an increase in temperature (20, 30, 40 ˚C) or increase in reaction time (5, 10, 20, 30 and 40 min) increased the absorbance of ceric (IV) sulphate solution. Absorbance was measured at five wavelengths (300,323,325,332 and 340 nm) and the maximum absorbance was obtained at 323nm.The absorbance of ceric (IV) sulphate was also measured in 4M, 5M and 6M H2SO4 .The maximum absorbance was obtained in 5M H2SO4. A simple, rapid and accurate method for the determination of vitamin C content using ceric (IV) sulphate was developed by indirect UV spectrophotometry.The method has been applied for the determination of vitamin C content in the dry fruits and leaves samples. Three extracting solutions were used: 4.5% metaphosphoric acid, acetic acid and distilled water. The first extracting solution gave comparatively high concentration of vitamin C in BL(465 ppm),followed in BF(380 ppm).In PL also it comparatively high content (315 ppm) was obtained, followed in PF(216 ppm).The second extracting solution gave high content(441 ppm) in BL ,followed in BF(361ppm),and in PF(306 ppm) followed in PL(198 ppm).The third extracting solution gave high content in PL(423 ppm) followed in PF(326 ppm),and in BL(283 ppm),and in BF(179 ppm).