Identification
A:
Thin-Layer Chromatographic Identification Test á201ñ
Test solution
Dilute a portion of Ophthalmic Solution with a mixture of chloroform and methanol (1:1)to obtain a solution having a concentration of about 0.3mg of ofloxacin per mL.
Standard solution
Dissolve an accurately weighed quantity of
USP Ofloxacin RSin a mixture of chloroform and methanol (1:1)to obtain a solution having a concentration of 3.0mg per mL.Transfer 5.0mLof this solution to a 50-mLvolumetric flask,add 5mLof water,dilute with a mixture of chloroform and methanol (1:1)to volume,and mix.
Application volume:
2µL.
Developing solvent system:
a mixture of chloroform,methanol,and a solution (1in 30)of ammonium hydroxide (150:75:15).Saturate a paper-lined chromatographic chamber with this mixture.
B:
The retention time of the ofloxacin peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay.
Assay
Mobile phase
Prepare a filtered and degassed mixture of sodium dodecyl sulfate (0.24%aqueous solution),acetonitrile,and glacial acetic acid (580:400:20).Make adjustments if necessary (see
System Suitabilityunder
Chromatography á621ñ).
0.05N Hydrochloric acid
Add 4.0mLof hydrochloric acid to 500mLof water,dilute with water to 1000mL,and mix.
Resolution solution
Prepare a solution of about 0.1mg of
USP Ofloxacin RSand about 2.4mg of propylparaben in each mLof acetonitrile.
Standard preparation
Quantitatively dissolve an accurately weighed quantity of
USP Ofloxacin RSin
0.05N Hydrochloric acidto obtain a solution having a known concentration of about 0.06mg per mL.
Assay preparation
Transfer an accurately measured volume of Ophthalmic Solution,equivalent to about 3mg of ofloxacin,to a 50-mLvolumetric flask,dilute with0.05N Hydrochloric acidto volume,and mix.
Chromatographic system (see Chromatography á621ñ)
The liquid chromatograph is equipped with a 294-nm detector and a 4.6-mm ×25-cm column that contains 5-µm packing L1.The flow rate is about 1.5mLper minute.The column temperature is maintained at a constant temperature of about 35

.Chromatograph the
Resolution solution,and record the peak responses as directed for
Procedure:the resolution,
R,between propylparaben and ofloxacin is not less than 2.Chromatograph the
Standard preparation,and record the peak responses as directed for
Procedure:the tailing factor is not more than 3;and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure
Separately inject equal volumes (about 20µL)of the
Standard preparationand the
Assay preparationinto the chromatograph,record the chromatograms,and measure the areas for the major peaks.Calculate the quantity,in mg,of ofloxacin (C
18H
20FN
3O
4)in each mLof the Ophthalmic Solution taken by the formula:
50(C/V)(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Ofloxacin RSin the
Standard preparation;Vis the volume,in mL,of Ophthalmic Solution taken to prepare the
Assay preparation;and
rUand
rSare the ofloxacin peak areas obtained from the
Assay preparationand the
Standard preparation,respectively.