Triiodomethane

CHI3 393.85[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 0.1g:a purple gas is evolved.

Loss on drying á731ñ— Dry it over silica gel for 24hours:it loses not more than 0.5%of its weight.

Residue on ignition á281ñ: not more than 0.1%.

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

Chloride á221ñ— Shake 3.0g of powdered Iodoform with 75mLof water for 1minute,allow to stand,and filter the supernatant.To 25mLof the filtrate add 6mLof 3Nnitric acid,and dilute with water to 40mL.This solution shows no more chloride than corresponds to 0.15mLof 0.020Nhydrochloric acid (0.011%).

Sulfate á221ñ— To 25mLof the filtrate obtained in the test for Chlorideadd 1mLof 3Nhydrochloric acid,and dilute with water to 40mL.This solution shows no more sulfate than corresponds to 0.17mLof 0.020Nsulfuric acid (0.017%).

Assay— Transfer about 200mg of Iodoform,previously dried over silica gel for 24hours and accurately weighed,to a 500-mLglass-stoppered conical flask.Add 20mLof alcohol,and swirl to dissolve.Add 30.0mLof 0.1Nsilver nitrate VSand 10mLof nitric acid,insert the stopper,and allow it to stand in a dark place for 16hours.Add 150mLof water and 5mLof ferric ammonium sulfate TS,and titrate the excess silver nitrate with 0.1Nammonium thiocyanate VS.Perform a blank determination (see Titrimetry á541ñ).Each mLof 0.1Nsilver nitrate is equivalent to 13.124mg of CHI3.

Expert Committee:(PA7)Pharmaceutical Analysis 7

USP28–NF23Page 1042

Phone Number:1-301-816-8394