CHI3

Triiodomethane 393.73 [75-47-8].

Packaging and storage— Preserve in tight, light-resistant containers, store at controlled room temperature, and prevent exposure to excessive heat.

Labeling— Label it to indicate that it is intended for use in compounding dosage forms for topical, periodontal, nasal, and intracavitary use only.

Identification— Heat 0.1 g: a purple gas is evolved.

Loss on drying 731— Dry it over silica gel for 24 hours: it loses not more than 0.5% of its weight.

Residue on ignition 281: not more than 0.1%.

Coloring matter, acids, and alkalies— Shake about 2 g of it with 5 mL of water for 1 minute, and filter: the filtrate is colorless and is neutral to litmus.

Chloride 221— Shake 3.0 g of powdered Iodoform with 75 mL of water for 1 minute, allow to stand, and filter the supernatant. To 25 mL of the filtrate add 6 mL of 3 N nitric acid, and dilute with water to 40 mL. This solution shows no more chloride than corresponds to 0.15 mL of 0.020 N hydrochloric acid (0.011%).

Sulfate 221— To 25 mL of the filtrate obtained in the test for Chloride add 1 mL of 3 N hydrochloric acid, and dilute with water to 40 mL. This solution shows no more sulfate than corresponds to 0.17 mL of 0.020 N sulfuric acid (0.017%).

Assay— Transfer about 200 mg of Iodoform, previously dried over silica gel for 24 hours and accurately weighed, to a 500-mL glass-stoppered conical flask. Add 20 mL of alcohol, and swirl to dissolve. Add 30.0 mL of 0.1 N silver nitrate VS and 10 mL of nitric acid, insert the stopper, and allow it to stand in a dark place for 16 hours. Add 150 mL of water and 5 mL of ferric ammonium sulfate TS, and titrate the excess silver nitrate with 0.1 N ammonium thiocyanate VS. Perform a blank determination (see Titrimetry 541). Each mL of 0.1 N silver nitrate is equivalent to 13.124 mg of CHI3.

Topic/Question	Contact	Expert Committee
Monograph	Behnam Davani, Ph.D., M.B.A. Senior Scientist 1-301-816-8394	(MDAA05) Monograph Development-Antivirals and Antimicrobials

USP32–NF27 Page 2664