Mouhannad AL.-Hachamii Sadiq J. Baqir Saadon A.Aowda Fatima A. Hussein, Dep.of chemistry, college of science, Babylon University
Ministry of Health Hilla city, Babylon
The goal of this search is to determine the concentration of vitamin C (Ascorbic acid ) in some of a Commercial Products, Vegetables and Fruit Juices by Redox Titration. A redox titration, involving an Iodometric method, has been used to do the analysis. The samples classified by their Vitamin C content. الخلاصة
الهدف من البحث لتحديد تركيز فيتامينC (حامض الاسكوربيك)في عدد من المنتجات التجارية والخضروات وعصائر الفواكه بواسطة التسحيح الاختزالي.التسحيح الاختزالي يتضمن طريقة اليودو ميتريا باستخدام التحليل.النماذج مصنفة حسب احتوائها لفيتامينC. Introduction
Vitamins are a group of small molecular compounds that are essential nutrients in many multi-cellular organisms, and humans in particular. L-Ascorbic acid was first isolated as a pure substance by Albert Azent-Gyorgi and Charles Kingin 1928 [Paulling ,1970] , an anti-oxidant and free radical scavenger, is found ubiquitously in fruit and vegetables such as citrus fruits (oranges, lemons, limes, tangerines etc.), melons, tomatoes, peppers, broccoli, green leafy vegetables such as spinach, potatoes and turnips, its quantitative determination is especially important in the production of wine, beer, milk, soft drinks and fruit juices, where it can be a quality indicator [Gerrior & Zizza,1994] .Given the essential role played in the human diet and necessary to growth and repair of tissues in all parts of human body .It is necessary to form collagen an important skin proteins ,scar tissue ,tendons, ligaments, and blood vessels. vitamin C is essential for the healing of wounds, and for the repair and maintenance of cartilage, bones and teeth [Mcevoy ,1993] . Since vitamin C is easily oxidized, storage and cooking in air leads to the eventual oxidation of vitamin C by oxygen in the atmosphere. In addition, ascorbic acid is water-solubility vitamin means that a significant amount of vitamin C present in a food can be lost by boiling and then discarding the cooking water [Mcevoy ,1993]. The formula for ascorbic acid is C6H8O6 , It occurs as a white or slightly yellow crystal or powder with a slight acidic test , Ascorbic Acid is freely soluble in water; sparingly soluble in alcohol; insoluble in chloroform, ether, and benzene [Moffat,1986]. The structures for the reduced (ascorbic acid) form and for the oxidized form (dehydroascorbic acid) are shown below: [pic]
The amount of ascorbic acid can be determined by a redox titration with a standardized solution of iodine. The iodine is reduced by the ascorbic acid to form iodide. As shown in the other half of this redox equation. [pic]
The titration end point is reached when a slight excess of iodine is added to the ascorbic acid solution [Bailey ,1974;Brody,1994;Pauling ,1976;Kalluer,1986]. Vitamin C deficiency leads to scurvy, a disease characterized by weakness, small hemorrhages throughout the body that cause gums and skin to bleed, and loosening of the teeth. Vitamin C can not synthesized through body cells, nor does it store it. It is therefore important to include plenty of vitamin C-containing foods in daily diet. vitamin C toxicity is very rare, because the body can not store the vitamin however ,amounts greater than 2000 mg/day are not recommended because such high doses can lead to stomach up set and diarrhea. The minimum daily requirement is 30 mg. Well-balanced diets provide adequate amounts of the vitamin as measured by the Recommended Daily Allowance (RDA) of about 75 mg per day for adults (aged 15 or older), less for children, and more for pregnant and lactating women. The...