Packaging and storage— Preserve in well-closed containers, and avoid prolonged exposure to temperatures exceeding 30.

Identification— Digest a quantity of Paste, equivalent to about 1 g of carboxymethylcellulose sodium, with 50 mL of water until solution is virtually complete, and filter: the filtrate responds to the following tests.

Consistency— Determine as directed in the test for Consistency under Petrolatum: the final average of the trials is not less than 30.0 mm and not more than 36.0 mm, indicating a consistency value between 300 and 360.

Microbial enumeration tests 61 and Tests for specified microorganisms 62— The total bacterial count does not exceed 1000 cfu per g, and the tests for Salmonella species and Escherichia coli are negative.

Loss on drying 731— Dry it at 105 for 3 hours: it loses not more than 2.0% of its weight.

Heavy metals, Method II 231: 0.005%, using 400 mg of Carboxymethylcellulose Sodium Paste and adding 1 mL of hydroxylamine hydrochloride solution (1 in 5) to the solution of the residue.

Assay— Transfer about 2 g of Paste, accurately weighed, to a glass-stoppered, 250-mL conical flask. Add 75 mL of glacial acetic acid, attach a condenser, and reflux for 2 hours. Cool, transfer the mixture to a 250-mL beaker with the aid of small volumes of glacial acetic acid, and titrate with 0.1 N perchloric acid in dioxane VS, determining the endpoint potentiometrically. Each mL of 0.1 N perchloric acid is equivalent to 29.67 mg of carboxymethylcellulose sodium.

Topic/Question	Contact	Expert Committee
Monograph	Hong Wang, Ph.D. Scientist 1-301-816-8345	(EM205) Excipient Monographs 2
61	Radhakrishna S Tirumalai, Ph.D. Senior Scientist 1-301-816-8345	(MSA05) Microbiology and Sterility Assurance
62	Radhakrishna S Tirumalai, Ph.D. Senior Scientist 1-301-816-8345	(MSA05) Microbiology and Sterility Assurance

USP32–NF27 Page 1803