Iodoform

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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CHI₃ 393.73

Triiodomethane CAS RN^®: 75-47-8; UNII: KX12J76489.

1 DEFINITION

lodoform, previously dried over silica gel for 24 h, contains NLT 99.0% and NMT 100.5% of iodoform (CHI₃).

2 IDENTIFICATION

A.

Sample: 0.1 g

Analysis: Heat the Sample.

Acceptance criteria: A purple gas is evolved.

3 ASSAY

3.1 PROCEDURE

Sample: 200 mg of lodoform, previously dried over silica gel for 24 h

Titrimetric system

(See Titrimetry (541).)

Mode: Residual titration

Titrant: 0.1 N silver nitrate VS

Back-titrant: 0.1 N ammonium thiocyanate VS

Endpoint detection: Visual

Analysis: Transfer the Sample to a 500-mL glass-stoppered conical flask. Add 20 mL of alcohol, and swirl to dissolve. Add 30.0 mL of Titrant and 10 mL of nitric acid, insert the stopper, and allow it to stand in a dark place for 16 h. Add 150 mL of water and 5 mL of ferric ammonium sulfate TS, and titrate the excess silver nitrate with Back-titrant. Perform a blank determination. Each mL of 0.1 N silver nitrate is equivalent to 13.124 mg of iodoform (CHI).

Acceptance criteria: 99.0%-100.5% on the previously dried basis

4 IMPURITIES

RESIDUE ON IGNITION (281): NMT 0.1%

CHLORIDE AND SULFATE, Chloride (221)

Sample solution: 3.0 g of powdered lodoform in 75 mL of water. Shake this solution for 1 min, allow to stand, and filter the supernatant. Use the filtrate for the analysis of Chloride and Sulfate.

Analysis: To 25 mL of the Sample solution add 6 mL of 3 N nitric acid, and dilute with water to 40 mL.

Acceptance criteria: 0.011%; this solution shows no more chloride than corresponds to 0.15 mL of 0.020 N hydrochloric acid.

CHLORIDE AND SULFATE, Sulfate (221)

Sample solution: Use as directed in the analysis of Chloride.

Analysis: To 25 mL of the Sample solution obtained in the test for Chloride add 1 mL of 3 N hydrochloric acid, and dilute with water to 40 mL.

Acceptance criteria: 0.017%; this solution shows no more sulfate than corresponds to 0.17 mL of 0.020 N sulfuric acid.

5 SPECIFIC TESTS

5.1 LOSS ON DRYING (731)

Analysis: Dry over silica gel for 24 h.

Acceptance criteria: NMT 0.5%

5.2 COLORING MATTER, ACIDS, AND ALKALIES

Sample: 2 g

Analysis: Shake the Sample with 5 mL of water for 1 min, and filter.

Acceptance criteria: The filtrate is colorless and is neutral to litmus.

6 ADDITIONAL REQUIREMENTS

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.