Packaging and storage— Preserve in well-closed containers.

Identification— Mix 1g with 10mLof water and 5mLof sulfuric acid in a porcelain dish.Evaporate the mixture until the excess water is removed,and continue heating the residue until dense,white fumes of sulfur trioxide appear.Cool,cautiously add 20mLof water,boil for a few minutes,and filter:there remains on the filter a gray residue (impure silica).The filtrate responds to the tests for Aluminum á191ñ.

Microbial limits á61ñ— It meets the requirements of the test for absence of Escherichia coli.

Loss on ignition á733ñ— Ignite between 550and 600:it loses not more than 15.0%of its weight.

Acid-soluble substances— Digest 1.0g with 20mLof 3Nhydrochloric acid for 15minutes,and filter:10mLof the filtrate,evaporated to dryness and ignited,leaves not more than 10mg of residue (2.0%).

Carbonate— Mix 1.0g with 10mLof water and 5mLof sulfuric acid:no effervescence occurs.

Iron— Triturate 2.0g in a mortar with 10mLof water,and add 0.50g of sodium salicylate:the mixture does not acquire more than a slight reddish tint.

Lead— To 1.0g contained in a centrifuge tube add 10mLof 1Nnitric acid,and digest for 1hour in a boiling water bath.Centrifuge until the solids are completely separated,and pour the supernatant into a 100-mLvolumetric flask.Add 5mLof 1Nnitric acid to the Kaolin,mix,and digest for 15minutes in a boiling water bath.Centrifuge,and add the supernatant to the previous extract in the volumetric flask.Dilute with water to volume.A50-mLportion of this solution contains not more than 5µg of lead (corresponding to not more than 0.001%of Pb)when tested as directed in the test for Lead á251ñ,using 3mLof Ammonium Citrate Solution,1mLof Potassium Cyanide Solution,and 500µLof Hydroxylamine Hydrochloride Solution.

Organic volatile impurities,Method IVá467ñ: meets the requirements.

Expert Committee:(PA6)Pharmaceutical Analysis 6

USP28–NF23Page 1096

Phone Number:1-301-816-8389