Edition: BP 2025 (Ph. Eur. 11.6 update)
Action and use
Astringent.
Preparations
Zinc Sulfate Capsules
Zinc Sulfate Tablets
DEFINITION
Content
99.0 per cent to 101.0 per cent.
CHARACTERS
Appearance
White or almost white, crystalline powder, or colourless, transparent crystals.
Solubility
Very soluble in water, practically insoluble in ethanol (96 per cent).
IDENTIFICATION
A. Solution S (see Tests) gives the reactions of sulfates (2.3.1).
B. Solution S gives the reaction of zinc (2.3.1).
C. It complies with the limits of the assay.
TESTS
Solution S
Dissolve 2.5 g in carbon dioxide-free water R and dilute to 50 mL with the same solvent.
Appearance of solution
Solution S is clear (2.2.1) and colourless (2.2.2, Method II).
pH (2.2.3)
4.0 to 5.6 for solution S.
Chlorides (2.4.4)
Maximum 300 ppm.
Dilute 3.3 mL of solution S to 15 mL with water R.
Iron (2.4.9)
Maximum 100 ppm.
Dilute 2 mL of solution S to 10 mL with water R. Use 0.5 mL of thioglycollic acid R in this test.
ASSAY
Dissolve 0.160 g in 5 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 17.95 mg of ZnSO4,H2O.
STORAGE
In a non-metallic container.
