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8:50 ©, , |, , Procedure:, , , , Ak“ ©, , =|, , , , TEST SAMPLE, , STANDARD COMPOUND, , , , Sample is dissolved in specific, amount of water and then, volume is made up to 40 ml, , 2 ml of standard solution of iron, diluted with water upto 40ml, , , , Add 2 ml of 20 % w/v of citric, acid (iron free), , Add 2 ml of 20 % w/v of citric, acid (iron free), , , , Add 2 drops of thioglycollic acid, , Add 2 drops of thioglycollic acid, , , , Add ammonia to make the, solution alkaline and adjust the, volume to 50 ml, , Add ammonia to make the, solution alkaline and adjust the, volume to 50 ml, , , , Keep aside for 5 min, , Keep aside for 5 min, , , , Color developed is viewed, , vertically and compared with, standard solution, , , , Color developed is viewed, vertically and compared with, , , , standard solution, , , , , , Observation:, , The purple color produce in sample solution should not be greater than, , standard solution., , If purple color produces in sample solution is less than the standard, solution, the sample will pass the limit test of sulphate and vice versa., , , , 44, , 45, , Limit Test fl, for IRON, , STANDARD i Indust 4 Min, ) sr, , =m

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850 H@-. AS) ©, , ¢ aw p & + FB, , Notes:, 1. Purified water is used for dilution, & it is free from dissolved, gas and impurities., , 1. Standard solution is prepared as it gives maximum permissible, limits for comparison., , 1. Ammonical alkaline medium is necessary for reaction of, thioglycollic acid with iron impurity., , 1. The formation of purple color is directly proportional to, amount of iron impurity present in the sample or substance., , 1. Citric acid is used to prevent precipitation of iron with, ammonia., , 1. Thioglycollic acid is used because it reacts with ferrous form of, iron and converts it into ferric form. Thus it forms purple color., , , , Limit Test, for IRON, , , , pane a STANDARD In Just 4 Min, re Mal eo i ae eee TEST, coe” of te, , 43 44 45