Product Name: E466 Sodium Carboxy Methyl Cellulose, Carboxy Methyl Cellulose, Cellulose Gum

Synonyms: CMC; NaCMC; Sodium CMC;

Definition: Carboxy methyl cellulose is the partial sodium salt of a carboxy­ methyl ether of cellulose, the cellulose being obtained directly from strains of fibrous plant material

      Einecs

      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

      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 carboxy­ methyl 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)

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 °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

E466-TDS-TDS-E466.pdf

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