| Synonyms | Cellulose gel |
| Definition | Microcrystalline cellulose is purified, partally depolymerised cellulose prepared by treating alpha-cellulose, obtained as a pulp from natural strains of fibrous plant material, with mineral acids. The degree of polymerisation is typically less than 400 |
| Chemical name | Cellulose |
| Einecs | 232-674-9 |
| Chemical formula | (C6H10O5)n |
| Molecular weight | About 36 000 |
| Assay | Not less than 97 % calculated as cellulose on the anhydrous basis |
| Description | A fine white or almost white odourless powder |
| Identification | |
A.Solubility | Insoluble in water, ethanol, ether and dilute mineral acids. Slightly soluble in sodium hydroxide solution |
B.Colour reaction | To 1 mg of the sample, add 1 ml of phosphoric acid and heat on a water bath for 30 minutes. Add 4 ml of a 1 in 4 solution of pyrocatechol in phosphoric acid and heat for 30 minutes. A red colour is produced |
C.To be identified by IR spectroscopy | |
D.Suspension test | Mix 30 g of the sample with 270 ml of water in a high-speed (12 000 rpm) power blender for 5 minutes. The resultant mixture will be either a free-following suspension or a heavy, lumpy suspension which flows poorly, if at all, settles only slightly and contains many trapped air bubbles. If a free-flowing suspension is obtained, transfer 100 ml into a 100-ml graduated cylinder and allow to stand for 1 hour. The solids settles and a supernatant liquid appears |
| Purity | |
| Loss on drying | Not more than 7 % (105 oC, 3 hours) |
| Water-soluble matter | Not more than 0,24 % |
| Sulphated ash | Not more than 0,5 % determined at 800 ± 25 oC |
| pH of a 10 % suspension in water | The pH of the supernatant liquid is between 5,0 and 7,5 |
| Starch | Not detectable |
| To 20 ml of the dispersion obtained in identification, test D, add a few drops of iodine solution and mix. No purplish to blue or blue colour should be produced |
| Particle size | Not less than 5 μm (not more than 10 % of particles of less than 5 μm) |
| Carboxyl groups | Not more than 1 % |
| 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 10 mg/kg |
