E 464 HYDROXYPROPYL METHYL CELLULOSE

Commission Directive 98/86/EC

Definition Hydroxypropyl methyl cellulose is cellulose obtained directly from natural strains of fibrous plant material and partially etherified with methyl groups and containing a small degree of hydroxypropyl substitution

Chemical name 2-Hydroxypropyl ether of methylcellulose

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

- CH₃

- CH₂CHOHCH₃

- CH₂CHO (CH₂CHOHCH₃) CH₃

- CH₂CHO[CH₂CHO (CH₂CHOHCH₃) CH₃]CH₃

Molecular weight From about 13 000 to 200 000

Assay Content not less than 19 % and not more than 30 % methoxyl groups (-OCH₃) and not less than 3 % and not more than 12 % hydroxypropoxyl groups (-OCH₂CHOHCH₃), on the anhydrous basis

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

Identification

A. Solubility Swelling in water, producing a clear to opalescent, viscous, colloidal solution. Insoluble in ethanol

B. Gas chromatography Determine the substituents by gas chromatography

Purity

Loss on drying Not more than 10 % (105 °C, 3 hours)

Sulphated ash Not more than 1,5 % for products with viscosities of 50 mPa.s or above

Not more than 3 % for products with viscosities below 50 mPa.s

pH of a 1 % colloidal solution Not less than 5,0 and not more than 8,0

Propylene chlorohydrins Not more than 0,1 mg/kg

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