Cellulose Acetate
Cellulose acetate
Cellulose, diacetate
[9035-69-2].
Cellulose, triacetate[9012-09-3].
(sel' ue lose as' e tate).
Cellulose acetate
Cellulose, diacetate
[9035-69-2].Cellulose, triacetate
[9012-09-3].DEFINITION
Cellulose Acetate is partially or completely acetylated cellulose. It contains NLT 29.0% and NMT 44.8%, by weight, of acetyl (C2H3O) groups, calculated on the dried basis. Its acetyl content is NLT 90.0% and NMT 110.0% of that indicated on the label.
IDENTIFICATION
• Infrared Absorption
Sample solution:
Prepare a solution (1 in 10) of Cellulose Acetate, previously dried, in dioxane.
Analysis:
Spread 1 drop of the Sample 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 105
for 1 h, and reassemble the dried plates.
for 1 h, and reassemble the dried plates.
Acceptance criteria:
The IR absorption spectrum exhibits maxima only at the same wavelengths as that of a similar preparation of USP Cellulose Acetate RS, treated in the same manner.
ASSAY
• Content of Acetyl
For Cellulose Acetate labeled to contain NMT 42.0% of acetyl groups
Sample:
2 g of Cellulose Acetate
Titrimetric system
(See Titrimetry 
541
.)
541.)
Mode:
Residual titration
Titrant:
1.0 N sodium hydroxide VS
Back-titrant:
1.0 N sulfuric acid VS
Endpoint detection:
Colorimetric
Analysis
Transfer the Sample to a 500-mL flask. Add 100 mL of acetone and 5–10 mL of water to the flask, insert the stopper into the flask, and stir with a magnetic stirrer until solution is complete. Add 30 mL of Titrant to the solution, with constant stirring. A finely divided precipitate of regenerated cellulose, free from lumps, is obtained. Insert the stopper into the flask, and stir with a magnetic stirrer for 30 min. Add 100 mL of water that has been preheated to 80, washing down the sides of the flask, stir for 2 min, and cool to room temperature. Titrate the excess sodium hydroxide solution with Back-titrant to a phenolphthalein endpoint. Treat a blank in the same manner.
, washing down the sides of the flask, stir for 2 min, and cool to room temperature. Titrate the excess sodium hydroxide solution with Back-titrant to a phenolphthalein endpoint. Treat a blank in the same manner.Calculate the percentage of acetyl in the portion of Cellulose Acetate taken:
Result = 4.305 × (B 
A)/W
A)/W| B | = | = volume of the Back-titrant consumed by the blank (mL) |
| A | = | = volume of the Back-titrant consumed by Cellulose Acetate (mL) |
| W | = | = weight of Cellulose Acetate taken, calculated on the dried basis (g) |
Acceptance criteria:
29.0%–44.8%, by weight, of acetyl (C2H3O) groups, on the dried basis
For Cellulose Acetate labeled to contain more than 42.0% of acetyl groups
Sample:
2 g of Cellulose Acetate
Titrimetric system
(See Titrimetry 541.)
541.)
Mode:
Residual titration
Titrant:
0.5 N hydrochloric acid VS
Back-titrant:
0.5 N sodium hydroxide VS
Endpoint detection:
Colorimetric
Analysis:
Transfer the Sample to a 500-mL conical flask. Add 30.0 mL of dimethyl sulfoxide and 100 mL of acetone, and stir for 16 h with the aid of a magnetic stirrer. Pipet 30 mL of 1 N sodium hydroxide VS slowly into the flask, with constant stirring. Insert the stopper into the flask, and stir for 6 min. Allow to stand without stirring for 60 min. Resume stirring, and add 100 mL of water that has been preheated to 80, washing down the sides of the flask. Stir for 2 min, and cool to room temperature. Add 4–5 drops of phenolphthalein TS, and titrate the excess sodium hydroxide solution with Titrant. Add an excess of 0.5 mL of Titrant. Stir for 5 min. Allow to stand for 30 min. Titrate with Back-titrant to 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.
, washing down the sides of the flask. Stir for 2 min, and cool to room temperature. Add 4–5 drops of phenolphthalein TS, and titrate the excess sodium hydroxide solution with Titrant. Add an excess of 0.5 mL of Titrant. Stir for 5 min. Allow to stand for 30 min. Titrate with Back-titrant to 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:
Result = 4.305 × n/W
| n | = | = corrected value of the net number of milliequivalents of sodium hydroxide consumed |
| W | = | = weight of Cellulose Acetate taken, calculated on the dried basis (g) |
Acceptance criteria:
29.0%–44.8%, by weight, of acetyl (C2H3O) groups, on the dried basis
IMPURITIES
Organic Impurities
• Procedure: Limit of Free Acid
Sample:
5 g
Titrimetric system
(See Titrimetry 541.)
541.)
Mode:
Direct titration
Titrant:
0.01 N sodium hydroxide VS
Endpoint detection:
Colorimetric
Analysis:
Transfer the Sample to a 250-mL flask. Add 150 mL of freshly boiled, cooled water, insert the stopper into the flask, swirl the suspension gently, and allow it to stand for 3 h. 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 the Titrant.
Calculate the percentage of free acid in the portion of Cellulose Acetate taken:
Result = 0.06005 × A/W
| A | = | = volume of Titrant consumed (mL) |
| W | = | = weight of the Cellulose Acetate taken, calculated on the dried basis (g) |
Acceptance criteria:
NMT 0.1%, calculated as acetic acid
SPECIFIC TESTS
• Loss on Drying 731:
Dry a sample at 105 for 3 h: it loses NMT 5.0% of its weight.
731:
Dry a sample at 105 for 3 h: it loses NMT 5.0% of its weight.
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight containers.
• Labeling:
The labeling states the nominal percentage content of acetyl.
• USP Reference Standards 11
11
USP Cellulose Acetate RS
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Robert H. Lafaver, M.S.
Scientific Liaison 1-301-816-8335 |
(EXC2010) Monographs - Excipients |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 1750
Pharmacopeial Forum: Volume No. 30(2) Page 699