Prepared at the 17th JECFA (1973), published in FNP 4 (1978) 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) | |
SYNONYMS | MEC; INS No. 465 |
DEFINITION | A mixed ether of cellulose, prepared from cellulose by treatment with alkali, dimethyl sulfate and ethyl chloride; both the methyl and ethyl groups are attached to the anhydroglucose units by ether linkages. The article of commerce can be specified further by viscosity. |
Chemical names | Ethyl methyl ether of cellulose |
C.A.S. number | 9004-69-7 |
Chemical formula | [C6H7O2(OH)x(OCH3)y(OC2H5)z]nwherez = 0.57 to 0.8y = 0.2 to 0.4x = 3 – (x + y)(y + z = degree of substitution) |
Structural formula | ![]() where R = H or CH3 or C2H5 |
Formula weight | Unsubstituted structural unit: 162.14Structural unit with a total degree of substitution of 0.77: 181Structural unit with a total degree of substitution of 1.2: 190Macromolecules: 30 000 – 40 000 (n about 200) |
Assay | Methyl Ethyl Cellulose contains, on the dried basis, not less than 3.5% and not more than 6.5% of methoxyl groups (-OCH3), not less than 14.5% and not more than 19.0% of ethoxyl groups (-OCH2CH3), and not less than 13.2% and not more than 19.6% of total alkoxyl groups, calculated as methoxyl (on the dry basis). |
DESCRIPTION | Hygroscopic and slightly yellowish odourless fibre or powder |
FUNCTIONAL USES | Emulsifier, stabilizer, thickening agent, foaming agent |
CHARACTERISTICS | |
IDENTIFICATION | |
Solubility | Swelling in water, producing a clear to opalescent, viscous, colloidal solution; insoluble in ethanol. |
Foam test | A 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 ether and alginates and natural gums). |
Precipitate formation | To 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 cellulose ethers from sodium carboxymethyl cellulose, gelatine, carob bean gum and tragacanth gum). |
Substituents | Determine the substituents by Gas Chromatography |
PURITY | |
Loss on drying | Not more than 15% for the fibrous form, and not more than 10% for the powdered form, after drying to constant weight |
Sulfated ash | Not more than 0.6%Test 1 g of the sample (Method I) |
Lead | Not 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 ASSAY | Determination of the Ethoxyl group (Ethoxyl and methoxyl can be separately determined by gas chromatography (Cobler, Samsel and Beaver, Talanta, 9, 473, 1962)).Apparatus:The apparatus for ethoxyl group determination is shown in the accompanying diagram. The boiling flask, D, is fitted with an aluminium foil-covered Vigreaux column, E, on the sidearm and with a bleeder tube through the neck and to the bottom of the flask for the introduction of steam and nitrogen. A steam generator, B, is attached to the bleeder tube through tube C, and a condenser, F, is attached to the Vigreaux column. The boiling flask and steam generator are immersed in an oil bath, A, equipped with a thermoregulator such that a temperature of 155o and the desired heating rate may be maintained. The distillate is collected in a 150-ml beaker, G, or other suitable container.![]() |