Iodine
I2 253.81
Iodine
[7553-56-2].
(eye' oh dine).
I2 253.81
Iodine
[7553-56-2].DEFINITION
Iodine contains NLT 99.8% and NMT 100.5% of I.
IDENTIFICATION
• A.
Solutions (1 in 1000) in chloroform and in carbon disulfide have a violet color.
• B.
Analysis:
To a saturated solution add starch–potassium iodide TS.
Acceptance criteria:
A blue color is produced. When the mixture is boiled, the color vanishes but reappears as the mixture cools, unless it has been subjected to prolonged boiling.
ASSAY
• Procedure
Sample:
500 mg of powdered Iodine
Analysis:
Place the Sample in a tared, glass-stoppered flask, insert the stopper, and add 1 g of potassium iodide dissolved in 5 mL of water. Dilute with water to 50 mL, add 1 mL of 3 N hydrochloric acid, 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 Iodine (I).
Acceptance criteria:
99.8%–100.5%
IMPURITIES
• Limit of Chloride or Bromide
Sample solution:
Triturate 250 mg of finely powdered Iodine with 10 mL of water, and filter the solution.
Analysis:
To the Sample solution add, dropwise, sulfurous acid (free from chloride), previously diluted with several volumes of water, until the iodine color just disappears. Add 5 mL of 6 N ammonium hydroxide, followed by 5 mL of silver nitrate TS in small portions. Filter, and acidify the filtrate with nitric acid.
Acceptance criteria:
The resulting liquid is not more turbid than a control made with the same quantities of the same reagents to which 0.10 mL of 0.020 N hydrochloric acid has been added, the sulfurous acid being omitted (0.028% as chloride).
• Limit of Nonvolatile Residue
Analysis:
Place 5.0 g in a tared porcelain dish, heat on a steam bath until the iodine has been driven off, and dry at 105
for 1 h.
for 1 h.
Acceptance criteria:
NMT 0.05% of the residue remains.
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight containers.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Behnam Davani, Ph.D., M.B.A.
Senior Scientific Liaison 1-301-816-8394 |
(SM12010) Monographs - Small Molecules 1 |
USP35–NF30 Page 3515