Hexachlorophene Cleansing Emulsion

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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1 DEFINITION

Hexachlorophene Cleansing Emulsion is Hexachlorophene in a suitable aqueous vehicle. It contains NLT 90.0% and NMT 110.0% of the labeled amount of hexachlorophene (C₁₃H₆C₆O₂). It contains no coloring agents.

2 IDENTIFICATION

A. THIN-LAYER CHROMATOGRAPHY

Diluent: Chloroform and methanol (1:1)

Standard solution: 6 mg/mL of USP Hexachlorophene RS in Diluent

Sample solution: Place a volume of Cleansing Emulsion, equivalent to 150 mg of hexachlorophene, in a glass-stoppered, 25-mL graduated cylinder. Dilute with Diluent to volume, and allow to stand for 5 min.

Chromatographic system

(See Chromatography (621), Thin-Layer Chromatography.)

Adsorbent: 0.25-mm layer of silica gel

Application volume: 10 µL

Developing solvent system: Toluene and glacial acetic acid (9:1)

Spray reagent: Dilute nitric acid (1 in 5)

Analysis: Develop in the Developing solvent system until the solvent front has moved 10 cm above the point of application. Remove the plate, mark the solvent front, and evaporate the solvent in a current of warm air. Spray the plate with Spray reagent, and warm on a hot plate until yellow spots appear.

Acceptance criteria: The R_F value of the principal spot of the Sample solution corresponds to that of the Standard solution.

3 ASSAY

3.1 PROCEDURE

Standard stock solution: 1 mg/mL of USP Hexachlorophene RS in methanol

Standard solution: 0.03 mg/mL of USP Hexachlorophene RS prepared as follows. Pipet 3 mL of Standard stock solution into a 100-mL volumetric flask. Add 1 mL of dilute hydrochloric acid (1 in 10), and add methanol to volume.

Sample stock solution: Nominally 0.3 mg/mL of hexachlorophene in methanol. Filter the solution through paper, taking adequate precautions to prevent evaporation.

Sample solution: 0.03 mg/mL of hexachlorophene prepared as follows. Pipet a 10-mL aliquot of the Sample stock solution into a 100-mL volumetric flask. Add 1 mL of dilute hydrochloric acid (1 in 10), and add methanol to volume.

Instrumental conditions

Mode: UV

Analytical wavelength: UV 299 nm

Cell: 1 cm

Blank: Methanol and hydrochloric acid (99:1)

Analysis: Concomitantly determine the absorbances of the Sample solution and the Standard solution.

Calculate the percentage of the labeled amount of hexachlorophene (C₁₃H₆C₆O₂) in the portion of Cleansing Emulsion taken:

Result = (A_U/A_S) x (C_S/C_U) x 100

A_U = absorbance of the Sample solution

A_S = absorbance of the Standard solution

C_S = concentration of the Standard solution (mg/mL)

C_U = nominal concentration of the Sample solution (mg/mL)

Acceptance criteria: 90.0%-110.0%

4 SPECIFIC TESTS

4.1 MICROBIAL ENUMERATION TESTS (61) and TESTS FOR SPECIFIED MICROORGANISMS (62)

It meets the requirements of the tests for the absence of Staphylococcus aureus and Pseudomonas aeruginosa.

4.2 PH (791)

Analysis: Place 20 mL of well-shaken Cleansing Emulsion and 10 mL of water in a glass-stoppered, 50-mL graduated cylinder, and determine the pH in a suitable pH meter, using a glass electrode and preferably a sleeve-type calomel electrode.

Acceptance criteria: 5.0-6.0

5 ADDITIONAL REQUIREMENTS

5.1 PACKAGING AND STORAGE

Preserve in tight, light-resistant, nonmetallic containers.

5.2 USP REFERENCE STANDARDS (11)

USP Hexachlorophene RS