Edition: BP 2025 (Ph. Eur. 11.6 update)
Action and use
Astringent.
Preparations
Zinc Sulfate Eye Drops
Zinc Sulfate Injection
Zinc Sulfate Lotion
DEFINITION
Content
99.0 per cent to 104.0 per cent.
CHARACTERS
Appearance
White or almost white, crystalline powder or colourless, transparent crystals, efflorescent.
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)
4.4 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 in this test 0.5 mL of thioglycollic acid R.
ASSAY
Dissolve 0.200 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 28.75 mg of ZnSO4,7H20.
STORAGE
In a non-metallic, airtight container.
