Packaging and storage— Preserve in tight containers.

USP Reference standards á11ñ— USP Polydimethylsiloxane RS.

Identification— The IRabsorption spectrum,determined in a 0.5-mm cell,of the solution of Emulsion prepared as directed in the Assay,the dilute hydrochloric acid being omitted,exhibits maxima only at the same wavelengths as that of a similar preparation of USP Polydimethylsiloxane RS.

Microbial limits á61ñ— Its total aerobic microbial count does not exceed 100cfu per g.

Heavy metals— Using Simethicone Emulsion instead of Simethicone,proceed as directed for Heavy metalsunder Simethicone.The limit is 5µg per g.

Defoaming activity—

Assay— Transfer an accurately weighed quantity of Emulsion,equivalent to about 50mg of simethicone,to a round,narrow-mouth,screw-capped,120-mLbottle,add 25.0mLof toluene,and swirl to disperse.Proceed as directed in the Assayunder Simethicone,beginning with “Add 50mLof dilute hydrochloric acid.”Calculate the quantity,in mg,of [-(CH3)2SiO-]nin each g of the Emulsion taken by the formula: in which Cis the concentration,in mg per mL,of USP Polydimethylsiloxane RSin the Standard preparation,Sis the weight,in g,of Emulsion taken,and AUand ASare the absorbances of the Assay preparationand the Standard preparation,respectively.

Expert Committee:(PA4)Pharmaceutical Analysis 4

USP28–NF23Page 1769

Phone Number:1-301-816-8251