keratolytic.
definition
carbamide.
content
98. 5 per cent to 101. 5 per cent (dried substance).
characters
appearance
white or almost white, crystalline powder or transparent crystals, slightly hygroscopic.
solubility
very soluble in water, soluble in alcohol, practically insoluble in methylene chloride.
identification
first identificationa, b.
second identificationa, c, d.
a. Melting point: 132 °c to 135 °c.
b. Infrared absorption spectrophotometry.
c. Dissolve 0. 1 g in 1 ml of water. add 1 ml of nitric acid. A white, crystalline precipitate is formed.
d. Heat 0. 5 g in a test tube until it liquefies and the liquid becomes turbid. Cool, dissolve in a mixture of 1 ml of dilute sodium hydroxide solution and 10 ml of water and add 0. 05 ml ofcopper sulphate solution. A reddish-violet colour is produced.
tests
solution s
dissolve 10. 0 g in water and dilute to 50 ml with the same solvent.
appearance of solution
the solution is clear and colourless.
to 2. 5 ml of solution s add 7. 5 ml of water.
alkalinity
to 2. 5 ml of solution s add 7. 5 ml of water, 0. 1 ml of methyl red solution and 0. 4 ml of 0. 01 m hydrochloric acid . The solution is red to orange.
biuret
maximum 0. 1 per cent.
ammonium
maximum 500 ppm, determined on 0. 1 ml of solution s.
heavy metals
maximum 10 ppm.
loss on drying
maximum 1. 0 per cent, determined on 1. 000 g by drying in an oven at 105 °c for 1 h.
sulphated ash
maximum 0. 1 per cent, determined on 1. 0 g.