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Cellulose Acetate

Cellulose acetate.
Cellulose,diacetate [9035-69-2].

Cellulose,triacetate [9012-09-3].
»Cellulose Acetate is partially or completely acetylated cellulose.It contains not less than 29.0percent and not more than 44.8percent,by weight,of acetyl (C2H3O)groups,calculated on the dried basis.Its acetyl content is not less than 90.0percent and not more than 110.0percent of that indicated on the label.
Packaging and storage— Preserve in tight containers.
Labeling— The labeling states the nominal percentage content of acetyl.
Identification— Prepare a solution of Cellulose Acetate (1in 10),previously dried,in dioxane.Spread 1drop of the solution on a sodium chloride plate,place a second sodium chloride plate over it,and spread the specimen between the plates.Separate the plates,heat them both at 105ºfor 1hour,and reassemble the dried plates:the IRabsorption spectrum exhibits maxima only at the same wavelengths as that of a similar preparation of USP Cellulose Acetate RS,treated in the same manner.
Loss on drying á731ñ— Dry it at 105ºfor 3hours:it loses not more than 5.0%of its weight.
Residue on ignition á281ñ: not more than 0.1%.
Free acid— Transfer about 5g,accurately weighed,to a 250-mLflask.Add 150mLof freshly boiled,cooled water,insert the stopper into the flask,swirl the suspension gently,and allow it to stand for 3hours.Filter through paper,and wash the flask and the filter with water,adding these washings to the filtrate.Add phenolphthalein TS,and titrate the combined filtrate and washings with 0.01Nsodium hydroxide VS.Calculate the percentage of free acid in the portion of Cellulose Acetate taken by the formula:
0.06005A/W,
in whichAis the volume,in mL,of 0.01Nsodium hydroxide consumed;andWis the weight,in g,of the Cellulose Acetate taken,calculated on the dried basis.Not more than 0.1%,calculated as acetic acid,is found.
Content of acetyl—
FOR CELLULOSE ACETATE LABELED TO CONTAIN NOT MORE THAN42.0%OF ACETYL GROUPS— Transfer about 2g,accurately weighed,to a 500-mLflask.Add 100mLof acetone and 5mLto 10mLof water to the flask,insert the stopper into the flask,and stir with a magnetic stirrer until solution is complete.Add 30mL,accurately measured,of 1.0Nsodium hydroxide VSto the solution,with constant stirring.Afinely divided precipitate of regenerated cellulose,free from lumps,is obtained.Insert the stopper into the flask,and stir with a magnetic stirrer for 30minutes.Add 100mLof water that has been preheated to 80º,washing down the sides of the flask,stir for 2minutes,and cool to room temperature.Titrate the excess sodium hydroxide solution with 1.0Nsulfuric acid VSto a phenolphthalein endpoint.Treat a blank in the same manner.Calculate the percentage of acetyl in the portion of Cellulose Acetate taken by the formula:
4.305(B–A)/W,
in whichBandAare the volumes,in mL,of 1.0Nsulfuric acid consumed by the blank and the Cellulose Acetate,respectively;andWis the weight,in g,of Cellulose Acetate taken,calculated on the dried basis.
FOR CELLULOSE ACETATE LABELED TO CONTAIN MORE THAN42.0%OF ACETYL GROUPS— Transfer about 2g,accurately weighed,to a 500-mLconical flask.Add 30.0mLof dimethyl sulfoxide and 100mLof acetone,and stir for 16hours with the aid of a magnetic stirrer.Pipet 30mLof 1Nsodium hydroxide VSslowly into the flask,with constant stirring.Insert the stopper into the flask,and stir for 6minutes.Allow to stand without stirring for 60minutes.Resume stirring,and add 100mLof water that has been preheated to 80º,washing down the sides of the flask.Stir for 2minutes,and cool to room temperature.Add 4to 5drops of phenolphthalein TS,and titrate the excess sodium hydroxide solution with 0.5Nhydrochloric acid VS.Add an accurately measured excess of about 0.5mLof 0.5Nhydrochloric acid VS.Stir for 5minutes.Allow to stand for 30minutes.Titrate with 0.5Nsodium hydroxide VSto a persistent pink endpoint,using a magnetic stirrer for agitation.Calculate the net number of milliequivalents of sodium hydroxide consumed,and correct this value by use of the average of two blank determinations run concomitantly through the entire procedure.Calculate the percentage of acetyl in the portion of Cellulose Acetate taken by the formula:
4.305n/W,
in whichn is the corrected value of the net number of milliequivalents of sodium hydroxide consumed;andWis the weight,in g,of Cellulose Acetate taken,calculated on the dried basis.NF23
Auxiliary Information— Staff Liaison:Justin Lane,B.S.,Scientific Associate
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 2984
Pharmacopeial Forum:Volume No.30(2)Page 699
Phone Number:1-301-816-8323