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.
A:
To about 30 mL of the solution add 3 mL of hydrochloric acid: a white precipitate is formed.
B:
To the remainder of the solution add an equal volume of
barium chloride TS: a fine, white, precipitate is formed.
C:
The filtrate from
Identification test
A responds to the tests for
Sodium 
191
.
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 limits 61—
The total bacterial count does not exceed 1000 cfu per g, and the tests for
Salmonella species and
Escherichia coli are negative.
Heavy metals, Method II 231—
Determine as directed in the test for
Heavy metals under
Methylcellulose, using a 400-mg specimen: the limit is 0.005%.
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.
