Ph Eur --- 9050-04-8
Action and use: Excipient in pharmaceutical products; bulk laxative.
DEFINITION
Calcium salt of a partly O-carboxymethylated cellulose.
CHARACTERS
Appearance: White or yellowish-white powder, hygroscopic after drying.
Solubility: Practically insoluble in acetone, in alcohol and in toluene. It swells with water to form a suspension.
IDENTIFICATION
A. Shake 0.1 g thoroughly with 10 ml of water. Add 2 ml of dilute sodium hydroxide solution and allow to stand for 10 min (solution A). Dilute 1 ml of solution A to 5 ml with water. To 0.05 ml add 0.5 ml of a 0.5 g/l solution of chromotropic acid, sodium salt in a 75 per cent m/m solution of sulphuric acid and heat on a water-bath for 10 min. A reddish-violet colour develops.
B. Shake 5 ml of solution A obtained in identification test A with 10 ml of acetone. A white, flocculent precipitate is produced.
C. Shake 5 ml of solution A obtained in identification test A with 1 ml of ferric chloride solution. A brown, flocculent precipitate is formed.
D. Ignite 1 g and dissolve the residue in a mixture of 5 ml of acetic acid and 10 ml of water. Filter if necessary and boil the filtrate for a few minutes. Cool and neutralise with dilute ammonia. The solution gives reaction of calcium.
TESTS
Solution S: Shake 1.0 g with 50 ml of distilled water, add 5 ml of dilute sodium hydroxide solution and dilute to 100 ml with distilled water.
Alkalinity: Shake 1.0 g thoroughly with 50 ml of carbon dioxide-free water and add 0.05 ml of phenolphthalein solution R . No red colour develops.
Chlorides: Maximum 0.36 per cent.
Sulphates: Maximum 1 per cent.
Heavy metals: Maximum 20 ppm.
Loss on drying: Maximum 10.0 per cent, determined on 1.000 g by drying in an oven at 105C for 4 h.
Sulphated ash: 10.0 per cent to 20.0 per cent, determined on 1.0 g in a platinum crucible.
