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Cellacefate

Cellulose,acetate,1,2-benzenedicarboxylate.
Cellulose acetate phthalate [9004-38-0].
»Cellacefate is a reaction product of phthalic anhydride and a partial acetate ester of cellulose.It contains not less than 21.5percent and not more than 26.0percent of acetyl (C2H3O)groups and not less than 30.0percent and not more than 36.0percent of phthalyl(o-carboxybenzoyl)(C8H5O3)groups,calculated on the anhydrous,acid-free basis.
Packaging and storage— Preserve in tight containers.
USP Reference standards á11ñ— USP Cellulose Acetate Phthalate RS.
Identification,Infrared Absorption á197Kñ— Do not dry specimens.
Viscosity á911ñ— Dissolve 15g,calculated on the anhydrous basis,in 85g of a mixture of 249parts of anhydrous acetone and 1part of water,by weight:the apparent viscosity (seeProcedure for Methylcellulose underViscosity á911ñ)is between 45and 90centipoises,determined at 25±0.2.
Water,Method Iá921ñ: not more than 5.0%,a mixture of dehydrated alcohol and methylene chloride (3:2)being used instead of methanol as the solvent.
Residue on ignition á281ñ: not more than 0.1%.
Limit of free acid— Transfer 3.0g,accurately weighed,to a glass-stoppered flask,add 100mLof dilute methanol (1in 2),insert the stopper in the flask,and shake for 2hours.Filter,and wash the flask and the filter with two 10-mLportions of the methanol solution,adding the washings to the filtrate.Titrate the combined filtrate and washings with 0.1Nsodium hydroxide VSto a phenolphthalein endpoint.Perform a blank determination on 120mLof the dilute methanol (1in 2).Calculate the percentage of free acid,B,by the formula:
0.8306A/W,
in whichAis the volume,in mL,of 0.1Nsodium hydroxide consumed,corrected for the blank;andWis the weight,in g,of the Cellacefate,calculated on the anhydrous basis.Not more than 3.0%,calculated as phthalic acid,is found.
Phthalyl content— Transfer about 1g,accurately weighed,to a conical flask,dissolve in 50mLof a mixture of alcohol and acetone (3:2),add phenolphthalein TS,and titrate with 0.1Nsodium hydroxide VS.Perform a blank determination,and make any necessary correction.Calculate the percentage of phthalyl,on the acid-free basis,by the formula:
100[(1.491A/W)–1.795B]/(100–B),
in whichAis the volume,in mL,of 0.1Nsodium hydroxide consumed after correction for the blank;Wis the weight,in g,of Cellacefate taken,calculated on the anhydrous basis;andBis the percentage of acid found in the test forLimit of free acid.
Content of acetyl— Transfer about 100mg,accurately weighed,to a glass-stoppered flask,and add 25.0mLof 0.1Nsodium hydroxide VS.Connect the flask to a reflux condenser,and reflux for 30minutes.Cool,add 5drops of phenolphthalein TS,and titrate with 0.1Nhydrochloric acid VS.Perform a blank determination.Calculate the free and combined acids,as acetyl,taken by the formula:
0.4305(A/W),
in whichAis the volume,in mL,of 0.1Nsodium hydroxide consumed after correction for the blank;andWis the weight,in g,of Cellacefate taken,on the anhydrous basis.Calculate the percentage of acetyl,on the acid-free basis,taken by the formula:
[100(P–0.5182B)/(100–B)]–0.5772C,
in whichPis the free and combined acids,as acetyl;Bis the percentage of acid found in the test forLimit of free acid;andCis the percentage of phthalyl found in the test forPhthalyl content.NF23
Auxiliary Information— Staff Liaison:Justin Lane,B.S.,Scientific Associate
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 2982
Pharmacopeial Forum:Volume No.30(2)Page 697
Phone Number:1-301-816-8323