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 (C
23H
30O
6),in each mLof the Ophthalmic Suspension taken by the formula:
50(C/V)(rU/rS),
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.