A: It meets the requirements of the Identificationtest in Gentamicin Sulfate Injection.

B: The retention time of the prednisolone acetate peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay for prednisolone acetate.

Diluting solvent— Mix 700mLof methanol and 300mLof water.

Mobile phase— Prepare a suitable mixture of water and acetonitrile (60:40),and pass through a suitable filter having a porosity of 1µm or less.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Transfer about 60mg of USP Prednisolone Acetate RS,accurately weighed,to a 50-mLvolumetric flask,dissolve in methanol,dilute with methanol to volume,and mix.Transfer 8.0mLof this solution to a second 50-mLvolumetric flask,dilute with Diluting solventto volume,and mix.This solution contains about 0.2mg of USP Prednisolone Acetate RSper mL.

Assay preparation— Transfer an accurately measured volume of well-mixed Ophthalmic Suspension,equivalent to about 10mg of prednisolone acetate,to a 50-mLvolumetric flask,dilute with Diluting solventto volume,and mix.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm ×30-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and measure the peak responses as directed under Procedure:the tailing factor for the analyte peak is not more than 1.25,the column efficiency is not less than 2000theoretical plates,and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 30µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of prednisolone acetate (C23H30O6),in each mLof the Ophthalmic Suspension taken by the formula: in which Cis the concentration,in mg per mL,of USP Prednisolone Acetate RSin the Standard preparation;Vis the volume,in mL,of Ophthalmic Suspension taken;and rUand rSare the prednisolone acetate peak responses obtained from the Assay preparationand the Standard preparation,respectively.