Microcrystalline Cellulose and Carboxymethylcellulose Sodium
» Microcrystalline Cellulose and Carboxymethylcellulose Sodium is a colloid-forming, attrited mixture of Microcrystalline Cellulose and Carboxymethylcellulose Sodium. It contains not less than 75.0 percent and not more than 125.0 percent of the labeled amount of carboxymethylcellulose sodium, calculated on the dried basis. The viscosity of its aqueous dispersion of percent by weight stated on the label is not less than 60.0 percent and not more than 140.0 percent of that stated on the label in centipoises.
Packaging and storage Preserve in tight containers, store in a dry place, and avoid exposure to excessive heat.
Labeling Label it to indicate the percentage content of carboxymethylcellulose sodium and the viscosity of the dispersion in water of the designated weight percentage composition.
A: Mix 6 g with 300 mL of water in a blender at 18,000 rpm for 5 minutes: a white, opaque, dispersion is produced which does not settle on standing.
B: Add several drops of the dispersion obtained in Identification test A to a solution of aluminum chloride (1 in 10): each drop forms a white, opaque globule which does not disperse on standing.
C: Add 3 mL of iodine TS to the dispersion obtained in Identification test A: no blue or purplish blue color is produced.
Viscosity 911 Determine the amounts of Microcrystalline Cellulose and Carboxymethylcellulose Sodium needed to prepare 600 g of a suitable dispersion, calculated on the dried basis. Transfer an accurately weighed amount of water to a 1000-mL blender bowl. Begin stirring with an 18,000 rpm blender at a reduced speed obtained by adjusting the voltage to 30 volts by means of a suitable transformer, and immediately add the accurately weighed portion of Microcrystalline Cellulose and Carboxymethylcellulose Sodium, taking care to avoid contacting the sides of the bowl with the powder. Continue stirring at this speed for 15 seconds following the addition of the powder, then increase the transformer setting to 115 volts, and mix for 2 minutes, accurately timed, at 18,000 rpm. Stop the blender, and lower the appropriate spindle of a suitable rotational viscosimeter into the dispersion. Thirty seconds after cessation of mixing, start the viscosimeter, and determine the viscosity using the appropriate spindle to obtain a scale reading between 10% and 90% of full-scale at a speed of 20 rpm. Determine the scale reading after 30 seconds of rotation, and calculate the viscosity, in centipoises, by multiplying the scale reading by the constant for the spindle used at 20 rpm.
pH 791: between 6.0 and 8.0, determined on the dispersion prepared in the test for Viscosity.
Loss on drying 731 Dry it at 105 to constant weight: it loses not more than 8.0% of its weight.
Residue on ignition 281: not more than 5.0%.
Heavy metals, Method II 231: 0.001%.
Assay for carboxymethylcellulose sodium Transfer about 2 g of Microcrystalline Cellulose and Carboxymethylcellulose Sodium, 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 29.6 mg of carboxymethylcellulose sodium.