Carbomer Homopolymer
(Title for this new monograph—to become official January 1, 2011)
(Prior to January 1, 2011, the current practice of labeling the article of commerce with the name Carbomer 934, Carbomer 934P, Carbomer 940, or Carbomer 941, whichever is appropriate, may be continued.)
Change to read:
» Carbomer Homopolymer is a high molecular weight polymer of acrylic acid cross-linked with allyl ethers of polyalcohols. Carbomer Homopolymer, previously dried, contains not less than 56.0 percent and not more than 68.0 percent of carboxylic acid (–COOH) groups.
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Packaging and storage—
Preserve in tight containers, at a temperature not exceeding 45
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Change to read:
Labeling—
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Identification—
A:
Infrared Absorption
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B:
Adjust a 1 in 100 dispersion of it with 1 N sodium hydroxide to a pH of about 7.5: a viscous gel is produced.
C:
Add 2 mL of a 1 in 10 aqueous solution of calcium chloride, while stirring, to 10 mL of the gel obtained from Identification test B: a white precipitate is immediately produced.
D:
Prepare a 1 in 100 dispersion of it. Add 0.5 mL of thymol blue TS to 10 mL of the dispersion: an orange color is produced. To another 10 mL of the dispersion add 0.5 mL of cresol red TS: a yellow color is produced.
Change to read:
Viscosity ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() Equip a suitable rotational viscometer
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Loss on drying
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Change to read:
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Heavy metals, Method II
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Limit of ethyl acetate and cyclohexane—
[note—This test is required only for those Carbomer Homopolymers whose labeling indicates that ethyl acetate or a mixture of ethyl acetate and cyclohexane was used in the polymerization process.]
Standard stock solution—
Transfer 5.0 mL of methanol to a 10-mL serum vial, insert a rubber septum, and seal with a metal cap. Add an accurately weighed quantity of about 25.0 µL of ethyl acetate and 20.0 µL of cyclohexane through the septum into the vial, and mix.
Standard solution—
Transfer 20.0 mL of methanol to a 30-mL serum vial, insert a rubber septum, and seal with a metal cap. Through the rubber septum, add 10 µL of methyl ethyl ketone (internal standard) and 50.0 µL of the Standard stock solution, and mix.
Test solution—
Transfer about 50 mg of Carbomer Homopolymer, accurately weighed, to a 30-mL serum vial, add 20 mL of methanol, insert a rubber septum, and seal with a metal cap. Through the rubber septum, add 10 µL of methyl ethyl ketone, and mix.
Chromatographic system (see Chromatography
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Procedure—
Proceed as directed under Carbomer Copolymer, except to calculate the percentages of ethyl acetate and cyclohexane in the portion of Carbomer Homopolymer taken by the formula:
100(WS / WT)(RU / RS)
in which WS is the weight, in mg, of ethyl acetate or cyclohexane, as appropriate, in the Standard solution; WT is the weight, in mg, of Carbomer Homopolymer taken to prepare the Test solution; and RU and RS are the peak area ratios of the relevant analyte peak to the methyl ethyl ketone peak obtained from the Test solution and the Standard solution, respectively: not more than 0.5% of ethyl acetate and not more than 0.3% of cyclohexane is found.
Change to read:
Limit of benzene—
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Solvent solution—
Quantitatively dissolve an accurately weighed quantity of benzene in dimethyl sulfoxide to obtain a solution having a concentration of about 1.0 mg per mL. Dilute this solution quantitatively, and stepwise if necessary, with organic-free water (see Residual Solvents
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Test solution—
Transfer about 50 mg of Carbomer Homopolymer, accurately weighed, to a 10-mL volumetric flask. Add about 7.5 mL of sodium chloride solution (2 in 100), and mix by mechanical means until homogeneous (usually about 30 minutes). Dilute with sodium chloride solution (2 in 100) to volume, and mix until homogeneous (usually less than 1 minute). [note—This preparation must be analyzed within 3 hours of preparation.]
Reference solution—
Transfer about 50 mg of Carbomer Homopolymer, accurately weighed, to a 10-mL volumetric flask. Add about 7.5 mL of sodium chloride solution (2 in 100), and mix by mechanical means until homogeneous (usually about 30 minutes). Add 1.0 mL of the Solvent solution, dilute with sodium chloride solution (2 in 100) to volume, and mix until homogeneous (usually less than 1 minute). This solution contains about 0.01 µg of benzene per mL.
Chromatographic system—
Proceed as directed in the test for Limit of benzene under Carbomer Copolymer.
Procedure—
Proceed as directed in the test for Limit of benzene under Carbomer Copolymer.
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Change to read:
Limit of acrylic acid—
0.01 M Phosphate buffer—
Dissolve 1.361 g of monobasic potassium phosphate in 1000 mL of water, and mix.
Solution A—
Use 0.01 M Phosphate buffer.
Solution B—
Prepare a filtered and degassed mixture of 0.01 M Phosphate buffer and acetonitrile (1:1, v/v).
Mobile phase—
Use variable mixtures of Solution A and Solution B as directed for Chromatographic system. Make adjustments if necessary (see System Suitability under Chromatography
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Solvent—
Dissolve 25 g of potassium alum in 1000 mL of water, and mix.
Standard solution—
Dissolve an accurately weighed quantity of acrylic acid in the Solvent, and dilute quantitatively, and stepwise if necessary, to obtain a solution having a concentration of about 12.5 µg per mL.
Test solution—
Mix about 100 mg of Carbomer Homopolymer, accurately weighed, with Solvent, and add Solvent to obtain 20.0 mL of suspension. Heat the suspension at 50
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Chromatographic system (see Chromatography
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Procedure—
Separately inject equal volumes (about 20 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the response for the acrylic acid peaks. Calculate the percentage of free acrylic acid in the portion of Carbomer Homopolymer taken by the formula:
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Content of carboxylic acid—
Proceed as directed in the test for Content of carboxylic acid under Carbomer Copolymer, except to calculate the percentage of carboxylic acid in the portion of Carbomer Homopolymer taken by the formula:
100(45.02VN/W)
in which W is the weight, in mg, of the portion of Carbomer Homopolymer taken; and the other terms are as defined therein.
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Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
Chromatographic Column—
USP32–NF27 Page 1190
Pharmacopeial Forum: Volume No. 34(1) Page 136
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.
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