Carboxy Methyl Cellulose Product Introduction

Carboxy Methyl Cellulose

Synonyms:  CMC; NaCMC; Sodium CMC; E466; Carboxymethyl Cellulose, Sodium Carboxymethyl Cellulose

Definition: Carboxy methyl cellulose is the partial sodium salt of a carboxymethyl ether of cellulose, the cellulose being obtained directly from  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 %

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)

Arsenic: Not more than 3 mg/kg

Lead: Not more than 2 mg/kg

Mercury: Not more than 1 mg/kg

Cadmium: Not more than 1 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

Description: Slightly hygroscopic white or slightly yellowish or greyish odourless  and tasteless, granular or fibrous powder

Identification

Solubility: Yields a viscous colloidal solution with water. Insoluble in ethanol

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)

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)

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

pH: Not less than 5.0 and not more than 8.5 (1 % colloidal solution)