Packaging and storage— Preserve in tight containers.

Labeling— Label it to indicate the maximum percentage of Loss on drying.

pHá791ñ: between 4.0and 8.5in a slurry (1in 20).

Loss on drying á731ñ— Dry it at 105for 2hours:it loses not more than the maximum percentage of its weight,as indicated in the labeling.

Sodium sulfate— Transfer about 1g of Dental-Type Silica,accurately weighed,to a platinum dish,wet with a few drops of water,add 15mLof perchloric acid,and place the dish on a hot plate.Add 10mLof hydrofluoric acid.Heat until copious fumes are evolved.Add 5mLof hydrofluoric acid,and again heat to copious fumes.Add about 5mLof boric acid solution (1in 25),and heat to fumes.Cool,and transfer the residue to a 400-mLbeaker with the aid of 10mLof hydrochloric acid.Adjust the volume with water to about 300mL,and bring to boiling on a hot plate.Add 20mLof hot barium chloride TS.Keep the beaker on the hot plate for 2hours,maintaining the volume above 200mL.After cooling,transfer the precipitate and solution to a dried,tared 0.8-µm porosity filter crucible.Wash the filter and precipitate 8times with hot water,dry the crucible at 105for 1hour,and weigh.The weight,multiplied by 0.6085,is the Sodium sulfatecontent of the amount of specimen taken.Not more than 4.0%is found.

Other requirements— It meets the requirements for Loss on ignition,Chloride,Arsenic,Heavy metals,and Assayunder Silicon Dioxide.

Expert Committee:(EMC)Excipients:Monograph Content

USP28–NF23Page 3073

Phone Number:1-301-816-8262