植物油中的碘值

Unsaturated fatty acids such as oleic acid and linoleic acid contained in fats and oils consume iodine, reacting with the double bond in unsaturated fatty acid. Iodine is expressed as “grams of iodine equivalent to halogen quantity of double bound (=unsaturated fatty acid) in oils and fats. As halogen, iodine bromide (IBr, Hanus method) or iodine monochloride (ICl, Wijs method) is used respectively. This application note describes the Wij’s method. An excessive volume of volume of iodine chloride solution is added to react with existing double bonds quantitatively in one by one ratio. Residual iodine chloride reacts with iodide to liberate iodine quantitatively. Iodine is titrated with sodium thiosulfate. 2Na2S2O3 + I2 􀃆 Na2S4O6 + 2NaI …………