Commission Directive 2008/84/EC (repealed)Show full title

E 466 SODIUM CARBOXY METHYL CELLULOSE

Synonyms	Carboxy methyl cellulose
	CMC
	NaCMC
	Sodium CMC
	Cellulose gum
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
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)
Assay	Content on the anhydrous basis not less than 99,5 %
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
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 oC 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