Carbomer Copolymer
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» Carbomer Copolymer is a high molecular weight copolymer of acrylic acid and a long chain alkyl methacrylate cross-linked with allyl ethers of polyalcohols.
Note—The heading of this monograph does not constitute the official title for a Carbomer Copolymer manufactured with the use of benzene. When benzene is used in the manufacturing process, the name will be Carbomer 1342, provided it complies with the existing requirements in the Carbomer 1342 monograph.
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Packaging and storage—
Preserve in tight containers, at a temperature not exceeding 45
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Labeling—
If benzene has been used in the manufacturing process, the name of the article will be Carbomer 1342, provided it complies with and is labeled in accordance with the requirements set forth in that monograph. If benzene is not used in the manufacturing process, label it to indicate whether it is Type A, B, or C; and label it to state the measured viscosity, ![]() ![]()
Identification—
A:
Infrared Absorption
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B:
Add about 5 g of Carbomer Copolymer to 500 mL of water, and stir: a dispersion is formed, with a foam layer that persists after allowing the dispersion to stand at room temperature for 1 hour.
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Viscosity ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]()
Table 1
![]() With the spindle rotating at 20 rpm, observe and record the scale reading. Calculate the viscosity, in millipascal seconds, by multiplying the scale reading by the constant for the spindle used at 20 rpm. The viscosity value so obtained is within the limits specified in
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Table 2
Loss on drying
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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 Copolymers where the 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 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 to obtain a solution containing 0.225 mg of ethyl acetate and 0.156 mg of cyclohexane.
Test solution—
Transfer about 50 mg of Carbomer Copolymer, accurately weighed, to a 30-mL serum vial, add 20.0 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—
Separately inject equal volumes (about 2 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the areas for the major peaks. Calculate the percentages of ethyl acetate and cyclohexane in the portion of Carbomer Copolymer taken by the formula:
100(WS / WT)(RU / RS)
in which WS is the weight, in mg, of ethyl acetate or cyclohexane in the Standard solution; WT is the weight, in mg, of Carbomer Copolymer 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 peaks 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.
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Limit of benzene—
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Solvent solution—
Dissolve an accurately weighed quantity of benzene quantitatively 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
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Test solution—
Transfer about 50 mg of Carbomer Copolymer, 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 Copolymer, 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 (see Chromatography
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Procedure—
Transfer 10.0 mL each of the Reference solution and the Test solution to separate headspace vials. Close the vials with a tight rubber membrane stopper coated with polytetrafluoroethylene, and secure with an aluminum crimped cap. Shake to obtain a homogeneous dispersion. Separately inject equal volumes (about 1 mL) of the gaseous phase of the Reference solution and the Test solution into the chromatograph, record the chromatograms, and measure the areas for the benzene peaks. The response of the benzene peak obtained from the Test solution is not greater than half of the benzene peak response obtained from the Reference solution: not more than 0.0002% is found.
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Limit of acrylic acid—
pH 3.0 Phosphate buffer—
Dissolve 6.80 g of monobasic potassium phosphate in about 300 mL of water, dilute with water to 500 mL, and mix. Dilute 100 mL of this solution with water to 1 L, adjust with phosphoric acid to a pH of 3.0 ± 0.1, and mix.
Mobile phase—
Use filtered and degassed pH 3.0 Phosphate buffer.
Standard solution—
Dissolve an accurately weighed quantity of acrylic acid in water, and dilute quantitatively, and stepwise if necessary, to obtain a solution having a known concentration of about 0.1 mg per mL. Dilute this solution quantitatively, and stepwise if necessary, with water to obtain a solution having a known concentration of about 25 µg per mL.
Test solution—
Transfer about 100 mg of Carbomer Copolymer, accurately weighed, to a tared serum vial. Add water to obtain about
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Chromatographic system (see Chromatography
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Procedure—
Separately inject equal volumes (about 10 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the responses for the acrylic acid peaks. Calculate the percentage of free acrylic acid in the portion of Carbomer Copolymer taken by the formula:
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Content of carboxylic acid—
Slowly add about 400 mg of Carbomer Copolymer, previously dried in vacuum at 80
![]() ![]() ![]() ![]() 100(45.02VN/W)
in which 45.02 is the molecular weight of the carboxylic acid (![]()
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
Chromatographic Column—
USP32–NF27 Page 1188
Pharmacopeial Forum: Volume No. 34(1) Page 134
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.
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