Packaging and storage
Preserve in tight containers.
Label it to indicate the viscosity in solutions of stated concentrations.
Add about 1 g of powdered Carboxymethylcellulose Sodium to 50 mL of water, while stirring to produce a uniform dispersion. Continue the stirring until a clear solution is produced, and use the solution for the following tests.
To 1 mL of the solution, diluted with an equal volume of water, in a small test tube, add 5 drops of 1-naphthol TS. Incline the test tube, and carefully introduce down the side of the tube 2 mL of sulfuric acid so that it forms a lower layer: a red-purple color develops at the interface.
To 5 mL of the solution add an equal volume of barium chloride TS
: a fine, white precipitate is formed.
A portion of the solution responds to the tests for Sodium 191
Determine the viscosity in a water solution at the concentration stated on the label. Using undried Carboxymethylcellulose Sodium, weigh accurately the amount that, on the dried basis, will provide 200 g of solution of the stated concentration. Add the substance in small amounts to about 180 mL of stirred water contained in a tared, wide-mouth bottle, continue stirring rapidly until the powder is well wetted, add sufficient water to make the mixture weigh 200 g, and allow to stand, with occasional stirring, until solution is complete. Adjust the temperature to 25 ± 0.2
, and determine the viscosity, using a rotational type of viscosimeter, making certain that the system reaches equilibrium before taking the final reading. The viscosity of solutions of 2% or higher concentration is not less than 80.0% and not more than 120.0% of that stated on the label; the viscosity of solutions of less than 2% concentration is not less than 75.0% and not more than 140.0% of that stated on the label.
between 6.5 and 8.5 in a solution (1 in 100).
Loss on drying 731
Dry it at 105
for 3 hours: it loses not more than 10.0% of its weight.
Heavy metals, Method II 231
Determine as directed in the test for Heavy metals
, using a 1.0-g specimen: the limit is 20 µg per g.
Organic volatile impurities, Method IV 467:
meets the requirements.
Transfer to a beaker about 500 mg of Carboxymethylcellulose Sodium, accurately weighed, add 80 mL of glacial acetic acid, heat the mixture on a boiling water bath for 2 hours, cool to room temperature, and titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically. Each mL of 0.1 N perchloric acid is equivalent to 2.299 mg of Na.