Tincture of iodine
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Tincture of iodine is a disinfectant, usually 2-7% potassium iodide or sodium iodide, and elemental iodine, dissolved in a mixture of ethanol and water. As in the case of Lugol's iodine, the role of iodide and water in the solution is to increase the solubility of the elemental iodine, by turning it to the soluble triiodide anion I3-. However, since iodine has moderate solubility in ethanol, it is also assisted by this solvent directly.
USP Tincture of Iodine is defined in the U.S. National Formulary (NF) as containing in each 100 mL, 1.8 to 2.2 grams of iodine, and 2.1 to 2.6 grams of sodium iodide. Alcohol is 50 ml and the balance is purified Water.
USP Strong Iodine Tincture is defined in the NF as containing in each 100 mL, 6.8 to 7.5 gram of iodine, and 4.7 to 5.5 gram of potassium iodide. Purified water is 50 mL and the balance is alcohol.
As both solutions contain elemental iodine, which is moderately toxic when ingested in amounts larger than those required to disinfect water, tincture of iodine is sold labeled "for external use only," and used primarily as a disinfectant. Although small amounts may be added to drinking water, iodine tincture is not an appropriate source of solely-nutritional iodine, which is better supplied in the form of the less toxic iodide or iodate salts. Nevertheless, the iodide in tincture of iodine does supply some nutritional iodine if it is used as a water disinfectant.
[edit] Overview
Tincture of iodine is often found in emergency survival kits, used both to disinfect wounds and to sanitize surface water for drinking. When an alcohol solution is not desirable, Lugol's iodine, an aqueous solution of iodine in potassium iodide solution, or povidone iodine (Betadine), a PVPI solution, can be used.
[edit] References
[edit] External links
- Health Canada Drinking water quality See the section on: water away from home
