Iodine number
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The iodine number (or "iodine adsorption number" or "iodine value") in chemistry is the mass of iodine in grams that is consumed by 100 grams of a chemical substance. An iodine solution is violet 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 violet is a measure of the amount of iodine sensitive reactive groups.
One application of the iodine number is the determination of saturation of fatty acids as double bonds in fatty acids also react with iodine compounds. 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 iodide which converts it to iodine. The iodine concentration is then determined by titration with sodium thiosulfate.
Standard methods for analysis are for example ASTM D1959-97 and DIN 53241.
