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 95.0percent and not more than 105.0percent of the labeled amount of ZnSO4. Packaging and storage— Preserve in tight containers. Identification— It responds to the tests for Zinc á191ñand for Sulfate á191ñ. Sterility á71ñ: meets the requirements.. pHá791ñ: between 5.8and 6.2;or,if it contains sodium citrate,between 7.2and 7.8. Assay— Pipet into a beaker a volume of Ophthalmic Solution,equivalent to about 25mg of zinc sulfate.Add 1mLof glacial acetic acid,and adjust by the dropwise addition of 6Nammonium hydroxide to a pHof between 5.0and 5.5.Add 1drop of copper ethylenediaminetetraacetate solution [prepared by mixing 1mLof cupric sulfate solution (1in 40)and 1mLof 0.1Medetate disodium]and 3drops of a 1in 1000solution of 1-(2-pyridylazo)-2-naphthol in anhydrous methanol,and titrate with 0.01Medetate disodium VS.Each mLof 0.01Medetate disodium is equivalent to 1.614mg of ZnSO4. Auxiliary Information— Staff Liaison:Lawrence Evans,III,Ph.D.,Scientist Expert Committee:(PA6)Pharmaceutical Analysis 6 USP28–NF23Page 2057 Phone Number:1-301-816-8389