- British Pharmacopoeia Volume I & II
- Monographs: Medicinal and Pharmaceutical Substances
Zinc Oxide |
 |
(Ph. Eur. monograph 0252)
ZnO 81.4 1314-13-2
Mild astringent.
Ph Eur
99.0 per cent to 100.5 per cent (ignited substance).
Soft, white or faintly yellowish-white, amorphous powder, free from gritty particles.
Practically insoluble in water and in ethanol (96 per cent). It dissolves in dilute mineral acids.
A. It becomes yellow when strongly heated; the yellow colour disappears on cooling.
B. Dissolve 0.1 g in 1.5 mL of dilute hydrochloric acid R and dilute to 5 mL with water R. The solution gives the reaction of zinc (2.3.1).
Shake 1.0 g with 10 mL of boiling water R. Add 0.1 mL of phenolphthalein solution R and filter. If the filtrate is red, not more than 0.3 mL of 0.1 M hydrochloric acid is required to change the colour of the indicator.
Dissolve 1.0 g in 15 mL of dilute hydrochloric acid R. It dissolves without effervescence and the solution is not more opalescent than reference suspension II (2.2.1) and is colourless (2.2.2, Method II).
Maximum 5 ppm, determined on 0.2 g.
Maximum 10 ppm.
Atomic absorption spectrometry (2.2.23, Method II).
Test solution Dissolve 2.0 g in 14 mL of a mixture of equal volumes of water R and cadmium- and lead-free nitric acid R, boil for 1 min, cool and dilute to 100.0 mL with water R.
Reference solutions Prepare the reference solutions using cadmium standard solution (0.1 per cent Cd) R and diluting with a 3.5 per cent V/V solution of cadmium- and lead-free nitric acid R.
Source Cadmium hollow-cathode lamp.
Wavelength 228.8 nm.
Atomisation device Air-acetylene or air-propane flame.
Maximum 200 ppm.
Dissolve 50 mg in 1 mL of dilute hydrochloric acid R and dilute to 10 mL with water R. Use in this test 0.5 mL of thioglycollic acid R.
Maximum 50 ppm.
Atomic absorption spectrometry (2.2.23, Method II).
Test solution Dissolve 5.0 g in 24 mL of a mixture of equal volumes of water R and cadmium- and lead-free nitric acid R, boil for 1 min, cool and dilute to 100.0 mL with water R.
Reference solutions Prepare the reference solutions using lead standard solution (0.1 per cent Pb) R and diluting with a 3.5 per cent V/V solution of cadmium- and lead-free nitric acid R.
Source Lead hollow-cathode lamp.
Wavelength 283.3 nm; 217.0 nm may be used depending on the apparatus.
Atomisation device Air-acetylene flame.
Maximum 1.0 per cent, determined on 1.00 g by ignition to constant mass at 500 ± 50 °C.
Dissolve 0.150 g in 10 mL of dilute acetic acid R. Carry out the complexometric titration of zinc (2.5.11).
1 mL of 0.1 M sodium edetate is equivalent to 8.14 mg of ZnO.
Ph Eur