CMC
Other name: carmellose; croscarmellose; Carboxymethyl Cellulose; Cellulose Carboxymethyl Ether; Cellulose-CM 23; cmc; Carboxy Methyl Cellulose; carboxy methyl cellulose; cm cellulose cation exchanger fast flow fibrous F; Carboxyl Methyl Cellulose
CAS No:000-11-7
Chemical name: Sodium salt of the carboxymethyl ether of cellulose
Chemical formula:
The polymers contain substituted anhydroglucose units with the
following general formula: C6H7O2(OR1)(OR2)(OR3), where R1, R2 R3 each may be one of the following:
H
CH2COONa
CH2COOH
Molecular weight:
Higher than approximately 17 000 (degree of polymerisation approximately 100)
Definition: Carboxy methyl cellulose is the partial sodium salt of a carboxymethyl ether of cellulose, the cellulose being obtained directly from natural strains of fibrous plant material
Description: Slightly hygroscopic white or slightly yellowish or greyish odourless and tasteless, granular or fibrous powder.
Identification:
A. Solubility Yields a viscous colloidal solution with water. Insoluble in ethanol.
B. Foam test A 0,1 % solution of the sample is shaken vigorously. No layer of foam appears. (This test permits the distinction of sodium carboxymethyl cellulose from other cellulose ethers)
C. Precipitate formation To 5 ml of a 0,5 % solution of the sample, add 5 ml of 5 % solution of copper sulphate or of aluminium sulphate. A precipitate appears. (This test permits the distinction of sodium carboxymethyl cellulose from other cellulose ethers and from gelatine, locust bean gum and tragacanth).
D. Colour reaction Add 0,5 g powdered carboxy methyl cellulose sodium to 50 ml of water, while stirring to produce an uniform dispersion. Continue the stirring until a clear solution is produced, and use the solution for the following test:
To 1 mg of the sample, diluted with an equal volume of water, in a small test tube, add 5 drops of 1-naphthol solution. Incline the test tube, and carefully introduce down the side of the tube 2 ml of sulphuric acid so that it forms a lower layer. A red-purple colour develops at the interface.
Purity:
Assay: Content on the anhydrous basis not less than 99,5 %
Degree of substitution Not less than 0,2 and not more than 1,5 carboxymethyl groups (CH2COOH) per anhydroglucose unit
Loss on drying: Not more than 12 % (105°C to constant weight)
pH of a 1 % colloidal solution: Not less than 5,0 and not more than 8,5
Arsenic: Not more than 3 mg/kg
Lead: Not more than 5 mg/kg
Mercury: Not more than 1 mg/kg
Cadmium: Not more than 1 mg/kg
Heavy metals (as Pb): Not more than 20 mg/kg
Total glycolate: Not more than 0,4 %, calculated as sodium glycolate on the anhydrous basis
Sodium: Not more than 12,4 % on the anhydrous basis
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