(Official January 1, 2007)

Mobile phase— Prepare a filtered and degassed mixture of water and acetonitrile (60:40). Make adjustments if necessary (see System Suitability under Chromatography 621).

Methanol-acetonitrile solution— Prepare a solution by mixing equal volumes of methanol and acetonitrile.

Standard preparation— Dissolve an accurately weighed quantity of USP Prednisolone Acetate RS in Methanol-acetonitrile solution, and dilute quantitatively, and stepwise if necessary, with Methanol-acetonitrile solution to obtain a solution having a known concentration of about 0.1 mg per mL.

Assay preparation— Transfer an accurately measured volume of Injectable Suspension, equivalent to about 50 mg of prednisolone acetate, to a 50-mL volumetric flask, add Methanol-acetonitrile solution to volume, and mix. Pipet 5 mL of this solution into a second 50-mL volumetric flask, dilute with Methanol-acetonitrile solution to volume, and mix.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm × 25-cm column that contains packing L1. The flow rate is about 1 mL per minute. Chromatograph the Standard preparation, and record the peak response as directed for Procedure: the capacity factor, k¢, is not less than 3.0, and the relative standard deviation for replicate injections is not more than 3.0%.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C23H30O6 in each mL of the Injectable Suspension taken by the formula: in which C is the concentration, in mg per mL, of USP Prednisolone Acetate RS in the Standard preparation, V is the volume, in mL, of Injectable Suspension taken, and rU and rS are the peak responses for prednisolone acetate obtained from the Assay preparation and the Standard preparation, respectively.