Sodium Sulfide Topical Gel
»Sodium Sulfide Topical Gel contains not less than 90.0percent and not more than 120.0percent of the labeled amount of sodium sulfide (Na2S·9H2O)in a suitable gel base.
Packaging and storage— Preserve in tight containers at controlled room temperature or in a cool place.
Identification— Proceed as directed for theIdentification test underSodium Sulfide.
pHá791ñ: between 11.5and 13.5.
Assay—
Diluent— Transfer 500.0mLof a 4.0Msodium hydroxide solution to a 1000-mLvolumetric flask,and add about 67.0g of edetate disodium and 36.0g of ascorbic acid,each accurately weighed.Dilute with water to volume,and mix.
Assay preparation— Transfer an accurately weighed portion of the Topical Gel,equivalent to about 30mg of sodium sulfide,to a 100-mLvolumetric flask,add 50mLofDiluent,and shake by mechanical means until the Topical Gel is dispersed.Dilute withDiluent to volume,and mix.
Procedure— Transfer 30.0mLof theAssay preparation to a suitable beaker,and titrate with 0.01Mlead perchlorate VS,determining the endpoint potentiometrically.Perform a blank determination,and make any necessary correction.Each mLof 0.01Mlead perchlorate is equivalent to 2.4018mg of sodium sulfide (Na2S·9H2O).
Auxiliary Information— Staff Liaison:Behnam Davani,Ph.D.,MBA,Senior Scientist
Expert Committee:(PA7)Pharmaceutical Analysis 7
USP28–NF23Page 1795
Pharmacopeial Forum:Volume No.28(2)Page 366
Phone Number:1-301-816-8394