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

Standard preparation— Dissolve an accurately weighed quantity of USP Chloramphenicol RSin Mobile phase,and dilute quantitatively,and stepwise if necessary,with Mobile phaseto obtain a solution having a known concentration of about 100µg 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 50mg of chloramphenicol,to a 100-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.Transfer 5.0mLof the resulting solution to a 25-mLvolumetric flask,dilute with Mobile phaseto 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 Procedurein the Assayunder Chloramphenicol.Calculate the quantity,in mg,of C11H12Cl2N2O5in each mLof the Otic Solution taken by the formula: in which Vis the volume,in mL,of Otic Solution taken,and the other terms are as defined therein.