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

Standard preparation— Dissolve an accurately weighed quantity of USP Chloramphenicol RS in Mobile phase, and dilute quantitatively, and stepwise if necessary, with Mobile phase to obtain a solution having a known concentration of about 100 µg per mL. 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 an accurately measured volume of Otic Solution, equivalent to about 50 mg of chloramphenicol, to a 100-mL volumetric flask, dilute with Mobile phase 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 C11H12Cl2N2O5 in each mL of the Otic Solution taken by the formula: in which V is the volume, in mL, of Otic Solution taken, and the other terms are as defined therein.