Hexachlorophene Cleansing Emulsion
»Hexachlorophene Cleansing Emulsion is Hexachlorophene in a suitable aqueous vehicle.It contains not less than 90.0percent and not more than 110.0percent of the labeled amount of C13H6Cl6O2.It contains no coloring agents.
Packaging and storage— Preserve in tight,light-resistant,non-metallic containers.
Identification— Place a volume of Emulsion,equivalent to about 150mg of hexachlorophene,in a glass-stoppered,25-mLgraduated cylinder,dilute with a mixture of equal volumes of chloroform and methanol to volume,mix,and allow to stand for about 5minutes.Apply 10µLof this solution and 10µLof a solution of USP Hexachlorophene RSin the same chloroform and methanol mixture containing 6mg per mLto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of silica gel.Develop the chromatogram in a solvent system consisting of a mixture of toluene and glacial acetic acid (9:1)until the solvent moves to about 10cm 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 dilute nitric acid (1in 5),and warm on a hot plate until yellow spots appear:the RFvalue of the principal spot obtained from the solution under test corresponds to that obtained from the Standard solution.
Microbial limits á61ñ— It meets the requirements of the tests for absence of Staphylococcus aureusand Pseudomonas aeruginosa.
pHá791ñ— Place 20mLof the well-shaken Emulsion and 10mLof water in a glass-stoppered,50-mLgraduated cylinder,mix,and determine the pHin a suitable pHmeter,using a glass electrode and preferably a sleeve-type calomel electrode:the pHis between 5.0and 6.0.
Assay—
Standard preparation— Weigh accurately about 50mg of USP Hexachlorophene RSinto a 50-mLvolumetric flask,add 10mLof methanol,shake until dissolved,add methanol to volume,and mix.Pipet 3mLof this solution into a 100-mLvolumetric flask,add 1mLof dilute hydrochloric acid (1in 10),add methanol to volume,and mix.
Assay preparation— Transfer an accurately weighed portion of Emulsion,equivalent to about 30mg of hexachlorophene,to a 100-mLvolumetric flask,add methanol to volume,and mix.Filter the solution through paper,taking adequate precautions to prevent evaporation.Pipet a 10-mLaliquot of the filtrate into a 100-mLvolumetric flask,add 1mLof dilute hydrochloric acid (1in 10),and add methanol to volume.
Procedure— Concomitantly determine the absorbances of the Assay preparationand the Standard preparationin 1-cm cells at the wavelength of maximum absorbance at about 299nm,with a suitable spectrophotometer,using a mixture of 99volumes of methanol and 1volume of hydrochloric acid as the blank.Calculate the quantity,in mg,of C13H6Cl6O2in the portion of Emulsion taken by the formula:
C(AU/AS),
in which Cis the concentration,in µg per mL,of USP Hexachlorophene RSin the Standard preparation,and AUand ASare the absorbances of the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Behnam Davani,Ph.D.,MBA,Senior Scientist
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 944
Phone Number:1-301-816-8394