Zinc Sulfate Ophthalmic Solution
» Zinc Sulfate Ophthalmic Solution is a sterile solution of Zinc Sulfate in Water rendered isotonic by the addition of suitable salts. It contains not less than 95.0 percent and not more than 105.0 percent of the labeled amount of ZnSO4.
Packaging and storage Preserve in tight containers.
Sterility 71: meets the requirements..
pH 791: between 5.8 and 6.2; or, if it contains sodium citrate, between 7.2 and 7.8.
Assay Pipet into a beaker a volume of Ophthalmic Solution, equivalent to about 25 mg of zinc sulfate. Add 1 mL of glacial acetic acid, and adjust by the dropwise addition of 6 N ammonium hydroxide to a pH of between 5.0 and 5.5. Add 1 drop of copper ethylenediaminetetraacetate solution [prepared by mixing 1 mL of cupric sulfate solution (1 in 40) and 1 mL of 0.1 M edetate disodium] and 3 drops of a 1 in 1000 solution of 1-(2-pyridylazo)-2-naphthol in anhydrous methanol, and titrate with 0.01 M edetate disodium VS. Each mL of 0.01 M edetate disodium is equivalent to 1.614 mg of ZnSO4.
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USP35NF30 Page 5077