- Iodine value
The iodine value (or "iodine adsorption value" or "iodine number" or "iodine index") in
chemistryis the mass of iodinein grams that is consumed by 100 grams of a chemical substance. An iodine solution is yellow/brown in color and any chemical group in the substance that reacts with iodine will make the color disappear at a precise concentration. The amount of iodine solution thus required to keep the solution yellow/brown is a measure of the amount of iodine sensitive reactive groups.
One application of the iodine number is the determination of the amount of unsaturation contained in fatty acids. This unsaturation is in the form of double bonds which react with iodine compounds. The higher the iodine number, the more
unsaturated fatty acidbonds are present in a fat. [http://domanski.cs.csi.cuny.edu/klibaner/LIPID.htm] In a typical procedure the acid is treated with an excess of the Hanus solution which is a solution of iodobromine (BrI). Unreacted iodobromine is reacted with potassium iodidewhich converts it to iodine. The iodine concentration is then determined by titration with sodium thiosulfate.
Standard methods for analysis are for example
ASTMD5768-02(2006) and DIN53241.
For a simple analysis, 0.2 grams of the fat is mixed with 20cm3 Wij's solution and 10cm3
1,1,1-trichloroethane. It is then left in the dark for 30mins. Next, 15cm3 of 10% potassium iodidesolution and 10cm3 of deionized water is added. This is then titrated against 0.1M sodium thiosulfate(VI) solution. 1cm3 of 0.1M sodium thiosulfate solution = 0.01269g of iodine. The difference between a control titration and the titration with the fat present multiplied by this factor gives the mass of iodine absorbed by the oil.
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iodine value — ▪ chemistry also called Iodine Number, in analytical chemistry, measure of the degree of unsaturation of an oil, fat, or wax; the amount of iodine, in grams, that is taken up by 100 grams of the oil, fat, or wax. Saturated oils, fats,… … Universalium
iodine value — jodo skaičius statusas T sritis chemija apibrėžtis Jodo kiekis (g), kurį prisijungia 100 g medžiagos. atitikmenys: angl. iodine number; iodine value rus. иодное число … Chemijos terminų aiškinamasis žodynas
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iodine number — jodo skaičius statusas T sritis chemija apibrėžtis Jodo kiekis (g), kurį prisijungia 100 g medžiagos. atitikmenys: angl. iodine number; iodine value rus. иодное число … Chemijos terminų aiškinamasis žodynas
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