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Preparation and Standardization of 0.05 M Iodine

Preparation and standardisation of 0.05 M Iodine solution using Arsenic Trioxide and Methyl Orange solution as indicator used in pharmaceutical analysis..

Iodine Solution Preparation

•  Dissolve about 14 g of iodine in a solution of 36 g of potassium iodide in 100 ml of water.
•  Add three drops of hydrochloric acid and dilute with water to 1000 ml.
•  Standardize the solution in the following manner.

Iodine Solution Standardization

•  Weigh accurately about 0.15 g of arsenic trioxide, previously dried at 105° for 1 hour.
•  Dissolve in 20 ml of 1M sodium hydroxide by warming, if necessary.
•  Dilute with 40 ml of water, add 0.1 ml of methyl orange solution and add drop wise dilute hydrochloric acid until the yellow color is changed to pink.
•  Add 2 g of sodium carbonate, dilute with 50 ml of water and add 3 ml of starch solution.
•  Titrate with the iodine solution until a permanent blue color is produced.
•  Store in amber-colored, glass stoppered bottles.
•  1 ml of 0.05 M iodine is equivalent to 0.004946 g of As2O3.
•  Calculate molarity of solution by following formula:

               As2O3 in mg
M = ----------------------------
         Iodine in ml  x 4.946

Also see: Determination of Shelf Life of Solutions in Laboratory

Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
Email: .moc.enilediugamrahp@ofni Need Help: Ask Question

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