A: The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay.

B: Place a number of Tablets,equivalent to about 1500mg of ciprofloxacin,in a suitable flask containing about 750mLof water,and sonicate for about 20minutes.Dilute with water to 1000mL,and mix.Centrifuge a portion of this suspension,and use the clear supernatant obtained as the test solution.Dissolve a quantity of USP Ciprofloxacin Hydrochloride RSin water to obtain a Standard solution containing 1.5mg per mL.Proceed as directed for Identificationtest Bunder Ciprofloxacin Hydrochloride,starting with “Separately apply,as 1-cm bands,5µLeach,”except to use 10µLeach of the test solution and the Standard solution:the specified result is obtained.

Medium: 0.01Nhydrochloric acid;900mL.

Apparatus 2: 50rpm.

Time: 30minutes.

Procedure— Determine the amount of ciprofloxacin hydrochloride (C17H18FN3O3·HCl)dissolved by employing UVabsorption at the wavelength of maximum absorbance at about 276nm on filtered portions of the solution under test,suitably diluted with Dissolution Medium,if necessary,in comparison with a Standard solution having a known concentration of USP Ciprofloxacin Hydrochloride RSin the same Medium.

Tolerances— An amount of ciprofloxacin hydrochloride (C17H18FN3O3·HCl)equivalent to not less than 80%(Q)of the labeled amount of ciprofloxacin (C17H18FN3O3)is dissolved in 30minutes.

Diluent— Prepare a filtered and degassed mixture of 0.025Mphosphoric acid,previously adjusted (with triethylamine)to a pHof 2.0±0.1,and acetonitrile (87:13).

Mobile phase— Prepare a filtered and degassed mixture of 0.025Mphosphoric acid,previously adjusted (with triethylamine)to a pHof 3.0±0.1,and acetonitrile (87:13).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Quantitatively dissolve an accurately weighed quantity of USP Ciprofloxacin Hydrochloride RSin Diluentto obtain a solution having a known concentration of about 0.2mg per mL.

Resolution solution— Dissolve a quantity of USP Ciprofloxacin Ethylenediamine Analog RSin the Standard preparationto obtain a solution containing about 0.05mg per mL.

Assay preparation— Transfer 5Tablets to a 500-mLvolumetric flask,add about 400mLof Diluent,and sonicate for about 20minutes.Dilute with Diluentto volume,and mix.Quantitatively dilute an accurately measured volume of this solution,previously filtered through a 0.45-µm membrane filter,with Diluentto obtain a solution containing the equivalent of about 0.20mg of ciprofloxacin per mL.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 278-nm detector and a 4.6-mm ×25-cm column that contains packing L1and is operated at 30±1.The flow rate is about 1.5mLper minute.Chromatograph the Resolution solution,and record the peak responses as directed for Procedure:the retention time for ciprofloxacin is between 6.4and 10.8minutes;the relative retention times are about 0.7for ciprofloxacin ethylenediamine analog and 1.0for ciprofloxacin;and the resolution,R,between the ciprofloxacin ethylenediamine analog peak and the ciprofloxacin peak is not less than 6.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency,determined from the ciprofloxacin peak,is not less than 2500theoretical plates;the tailing factor for the ciprofloxacin peak is not more than 2.0;and the relative standard deviation for replicate injections is not more than 1.5%.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparation into the chromatograph,record the chromatograms,and measure the peak areas for the major peaks.Calculate the quantity,in mg,of ciprofloxacin (C17H18FN3O3)in each Tablet taken by the formula: in which 331.34and 367.81are the molecular weights of ciprofloxacin and anhydrous ciprofloxacin hydrochloride,respectively;Cis the concentration,in mg per mL,of USP Ciprofloxacin Hydrochloride RSin the Standard preparation,calculated on the anhydrous basis;Lis the labeled quantity,in mg,of ciprofloxacin in each Tablet;Dis the concentration,in mg per mL,of ciprofloxacin in the Assay preparation,based on the labeled quantity per Tablet and the extent of dilution;and rUand rSare the ciprofloxacin peak areas obtained from the Assay preparationand the Standard preparation,respectively.