Carbomer 941
(kar' boe mer).
(Any article currently titled Carbomer 941 that is manufactured without the use of benzene will be officially titled Carbomer Homopolymer after January 1, 2011, and will meet the requirements of the new Carbomer Homopolymer monograph after January 1, 2007.)
» Carbomer 941 is a high molecular weight polymer of acrylic acid cross-linked with allyl ethers of pentaerythritol. Carbomer 941, previously dried in vacuum at 80 for 1 hour, contains not less than 56.0 percent and not more than 68.0 percent of carboxylic acid (–COOH) groups. The viscosity of a neutralized 0.5 percent aqueous dispersion of Carbomer 941 is between 4000 and 11,000 mPa·s.
[note—Effective January 1, 2011, the heading of this monograph will no longer constitute the official title for Carbomer 941 manufactured without the use of benzene. When benzene is not used in the manufacturing process, the name of the article will be Carbomer Homopolymer and will meet the requirements of the Carbomer Homopolymer monograph. ]
Packaging and storage— Preserve in tight containers. No storage requirements specified.
Labeling— Label it to indicate that it is not intended for internal use. A carbomer homopolymer manufactured using benzene and complying with the unique requirements of this monograph will be officially titled Carbomer 941 and will not be referred to as Carbomer Homopolymer.
Viscosity— Proceed as directed in the test for Viscosity under Carbomer 934P, except to use a spindle having a disk about 2.1 cm in diameter and 0.2 cm high, attached to a shaft 0.3 cm in diameter, the distance from the top of the disk to the lower tip of the shaft being 2.7 cm, and the immersion depth being 4.9 cm1. The viscosity is between 4000 and 11,000 mPa·s.
Limit of benzene— Proceed as directed in the test for Limit of benzene under Carbomer 934P, except to use about 20 mg of Carbomer 941, accurately weighed, instead of about 1 g of Carbomer 934P, to prepare the Test solution. Calculate the percentage of benzene in the portion of Carbomer 941 taken by the formula:
10(C/W)(rU / rS)
in which C is the concentration, in µg per mL, of benzene in the Standard solution; W is the weight, in mg, of Carbomer 941 taken to prepare the Test solution; and rU and rS are the benzene peak responses obtained from the Test solution and the Standard solution, respectively: not more than 0.5% is found.
Other requirements— It meets the requirements for Identification, Loss on drying, Heavy metals, and Assay for carboxylic acid content under Carbomer 934P.

1  Available as an RV5 spindle from Brookfield, or the equivalent.
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Topic/Question Contact Expert Committee
Monograph Robert H. Lafaver, M.S.
Scientific Liaison
(EXC2010) Monographs - Excipients
USP35–NF30 Page 1730
Pharmacopeial Forum: Volume No. 34(1) Page 133