(Official January 1, 2007)

Mobile phase and Chromatographic system—Proceed as directed in the Assay under Chloramphenicol.

Standard preparation— Transfer about 37.5 mg of USP Chloramphenicol RS and 37.5J mg of USP Hydrocortisone Acetate RS, both accurately weighed, J being the ratio of the labeled amount, in mg, of hydrocortisone acetate to the labeled amount, in mg, of chloramphenicol in the Chloramphenicol and Hydrocortisone Acetate for Ophthalmic Solution, to a 100-mL volumetric flask, add 15 mL of water and 75 mL of methanol, sonicate for a few seconds, dilute with methanol to volume, and mix. Transfer 5.0 mL of the resulting solution to a 25-mL volumetric flask, dilute with Mobile phase to volume, and mix. Filter a portion of this solution through a 0.5-µm or finer porosity filter, and use the clear filtrate as the Standard preparation.

Assay preparation— Transfer the contents of an accurately counted number of containers of Chloramphenicol and Hydrocortisone Acetate for Ophthalmic Solution, equivalent to about 37.5 mg of chloramphenicol, to a 100-mL volumetric flask with the aid of 5 mL of water for each 12.5 mg of chloramphenicol contained therein. Wash each container with methanol, and add the washings to the volumetric flask. Dilute with methanol to volume, and mix. Transfer 5.0 mL of the resulting solution to a 25-mL volumetric flask, dilute with Mobile phase to volume, and mix. Filter a portion of this solution through a 0.5-µm or finer porosity filter, and use the clear filtrate as the Assay preparation.

Procedure— Proceed as directed for Procedure in the Assay under Chloramphenicol. Calculate the quantity, in mg, of chloramphenicol (C11H12Cl2N2O5) in each container taken by the formula: in which N is the number of containers taken, and the other terms are as defined therein. Calculate the quantity, in mg, of hydrocortisone acetate (C23H32O6) in each container taken by the formula: in which C is the concentration, in mg per mL, of USP Hydrocortisone Acetate RS in the Standard preparation, N is the number of containers taken, and rU and rS are the hydrocortisone acetate peak responses obtained from the Assay preparation and the Standard preparation, respectively.