Strong Iodine Solution
» Strong Iodine Solution contains, in each 100 mL, not less than 4.5 g and not more than 5.5 g of iodine (I), and not less than 9.5 g and not more than 10.5 g of potassium iodide (KI).
Strong Iodine Solution may be prepared by dissolving 50 g of Iodine and 100 g of Potassium Iodide in 100 mL of Purified Water, then adding Purified Water to make the product measure 1000 mL.
Packaging and storage—
Preserve in tight containers, preferably at a temperature not exceeding 35
.
.
Identification—
A:
Dilute 1 drop with 10 mL of water, and add 1 mL of starch TS: a deep blue color is produced.
B:
Evaporate a few mL on a steam bath to dryness, and ignite gently to volatilize any free iodine: the residue responds to the tests for Potassium 
191
and for Iodide 191.
191 and for Iodide 191.
Assay for iodine—
Transfer 10.0 mL of Solution into a glass-stoppered, 500-mL flask, add 10 mL of water, and titrate with 0.1 N sodium thiosulfate VS, adding 3 mL of starch TS as the endpoint is approached. Each mL of 0.1 N sodium thiosulfate is equivalent to 12.69 mg of I.
Assay for potassium iodide—
Transfer 10.0 mL of Solution to a glass-stoppered, 500-mL flask, add 30 mL of water and 50 mL of hydrochloric acid, cool to room temperature, and titrate with 0.05 M potassium iodate VS until the dark brown solution that is produced becomes pale brown. Add 1 mL of amaranth TS, and continue the titration slowly until the red color just changes to yellow. The difference between the number of mL of 0.05 M potassium iodate used and half the number of mL of 0.1 N sodium thiosulfate used in the Assay for iodine, multiplied by 16.60, represents the number of mg of KI in the volume of the Solution taken.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Leonel M. Santos, Ph.D.
Senior Scientific Liaison 1-301-816-8168 |
(SM12010) Monographs - Small Molecules 1 |
USP35–NF30 Page 3516