Calcium polycarbophil [9003-97-8].

Packaging and storage— Preserve in tight containers.

Identification— When tested as directed in the test forAbsorbing power,it absorbs about 35times its original weight.

Loss on drying á731ñ— Dry it in vacuum at 130for 4hours:it loses not more than 10.0%of its weight.

Absorbing power— Transfer about 250mg,accurately weighed,to a tared 50-mLcentrifuge tube fitted with a tight closure.Add 35mLof 0.1Nhydrochloric acid to the tube,seal the tube,and shake by mechanical means for 30minutes.Centrifuge at 2000rpm for 20minutes,and decant and discard the supernatant.[NOTE—Exercise care to avoid any loss of particles.]Add 35mLof 0.1Nhydrochloric acid,and shake for 30minutes.Centrifuge,decanting and discarding the supernatant.Repeat the foregoing steps,using water instead of acid.Add 35mLof a sodium bicarbonate solution (15in 1000),and shake,venting as necessary to release any carbon dioxide liberated.Shake for 1hour,centrifuge,and decant the supernatant.Add 35mLof sodium bicarbonate solution (15in 1000),and shake for 1hour.Allow the tube and contents to stand overnight or until the contents have settled,and centrifuge.Withdraw the supernatant,and weigh the tube and contents.Calculate the weight of sodium bicarbonate solution absorbed:not less than 35.0g of the sodium bicarbonate solution is absorbed by 1.0g of Calcium Polycarbophil,calculated on the dried basis.

Organic volatile impurities,Method IVá467ñ: meets the requirements.

Content of calcium— Transfer about 2g of Calcium Polycarbophil,accurately weighed,to a tared crucible.Cover,leaving the lid slightly ajar,and place in a muffle furnace.Heat to 600over 2hours,increase the temperature to 1000over 1hour,and maintain at 1000for 1hour.Allow to cool slowly.Dissolve the residue in dilute hydrochloric acid (1in 5),quantitatively transfer with the aid of dilute hydrochloric acid (1in 5)to a 100-mLvolumetric flask,and dilute with dilute hydrochloric acid (1in 5)to volume.Pipet 15mLof this solution into a 250-mLbeaker,and add,while stirring with a magnetic stirrer,100mLof water,20.0mLof 0.05Medetate disodium VS,and 300mg of hydroxy naphthol blue.Adjust with 1Nsodium hydroxide solution to a pHof 9.0to 9.5.Adjust with about 10mLof 2Nsodium hydroxide to a pHof 12.4.Titrate with 0.05Medetate disodium VSto a persistent blue endpoint.Each mLof 0.05Medetate disodium is equivalent to 2.004mg of calcium (Ca).The content of Ca found is not less than 18.0%and not more than 22.0%,calculated on the dried basis.

Expert Committee:(PA4)Pharmaceutical Analysis 4

USP28–NF23Page 333

Phone Number:1-301-816-8251