(kar' boe mer).
(Any article currently titled Carbomer 940 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 940 is a high molecular weight polymer of acrylic acid cross-linked with allyl ethers of pentaerythritol. Carbomer 940, 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 940 is between 40,000 and 60,000 mPa·s.
[noteEffective January 1, 2011, the heading of this monograph will no longer constitute the official title for Carbomer 940 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 940 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 shaft about 0.3 cm in diameter, the distance from the top of the shaft to the lower tip of the shaft being 5.0 cm, and the immersion depth being 5.5 cm.1 The viscosity is between 40,000 and 60,000 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 940, 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 940 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 940 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 RV7 spindle from Brookfield, or the equivalent.