Methyl cellulose – JECFA specification

 Prepared at the 28th JECFA (1984), published in FNP 31/2 (1984) and in FNP 52 (1992). Metals and arsenic specifications revised at the 57th JECFA (2001). A group ADI ‘not specified’ for modified celluloses was established at the 35th JECFA (1989)
SYNONYMSCellulose methyl ether; INS No. 461
DEFINITIONThe methyl ether of cellulose, prepared from wood pulp or cotton by treatment with alkali and methylation of the alkali cellulose with methyl chloride. The article of commerce can be specified further by viscosity.
Chemical namesMethyl ether of cellulose; Cellulose methyl ether
C.A.S. number9004-67-5
Chemical formula[C6H7O2(OH)x(OCH3)y]nwherex = 1.00 to 1.55y = 2.00 to 1.45x+y = 3.00(y = degree of substitution)
Structural formula
where R = H or CH3
Formula weightUnsubstituted structural unit: 162.14Structural unit with total degree of substitution of 1.45 : 182Structural unit with total degree of substitution of 2.00 : 190Macromolecules: from about 20 000 (n about 100) up to about 380 000 (n about 2,000)
AssayNot less than 25% and not more than 33% of methoxyl groups (Some products of commerce designated “methyl cellulose” also contain components substituted with small amounts (max. 5%) of hydroxyethyl and/or hydroxypropyl groups. Development of separate specifications for these products should be considered).
DESCRIPTIONHygroscopic white or off-white, odourless fine granules, filaments or powder
FUNCTIONAL USESThickening agent, emulsifier, stabilizer
SolubilitySwelling in water, producing a clear to opalescent, viscous, colloidal solution; insoluble in ethanol, ether and chloroform; soluble in glacial acetic acid
Foam testAn 0.1% solution of the sample is shaken vigorously. A layer of foam appears. (This test permits the distinction of sodium carboxymethyl cellulose from other cellulose ethers.)
Precipitate formationTo 5 ml of an 0.5% solution of the sample, add 5 ml of a 5% solution of copper sulfate or of aluminium sulfate. No precipitate appears. (This test permits the distinction of sodium carboxymethyl cellulose from other cellulose ethers.)
Loss on dryingNot more than 10% (105o, 3 h)
pH5.0 – 8.0 (1 in 100 soln)
Sulfated ashNot more than 1.5%Test 1 g of the sample (Method I)
LeadNot more than 2 mg/kgDetermine using an atomic absorption technique appropriate to the specified level. The selection of sample size and method of sample preparation may be based on the principles of the method described in Volume 4, “Instrumental Methods.”
METHOD OF ASSAYDetermine the content of methoxyl groups by the method for Ethoxyl and Methoxyl Group Determination (see Volume 4).