A: The RFvalue of the principal spot observed in the chromatogram of the Test preparationobtained as directed in the Chromatographic puritytest corresponds to that obtained from the Standard preparation.

B: The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparationas obtained in the Assay.

Test preparation— [NOTE—Apply a quantity of extractives from Oral Solution to the chromatographic plate so as to achieve a nominal loading of 200µg of ranitidine.]Transfer a weighed quantity of Oral Solution,equivalent to 10mg of ranitidine,to a suitable syringe.Attach the tip of the syringe to the top of a cartridge (11mm ×12mm)of volume 0.5mLcontaining 0.4g of an L1packing for high-pressure liquid chromatography that has been previously prepared by passage of 10mLof methanol followed by passage of 20mLof 0.5Mammonia solution.Add 2.0mLof 0.5Mammonia solution to the syringe and force the mixture slowly through the cartridge.Repeat with 2further 3-mLportions of 0.5Mammonia solution.Discard all the liquid that has traversed the cartridge.Pass 5mLof a mixture of 0.1Mhydrochloric acid and methanol (3:1)through the cartridge,and collect the eluant in a clean round-bottom,25-mLflask.Repeat this with another 5-mLportion of the same eluting mixture and collect the eluant in the same flask.Evaporate the contents of the flask to dryness at a temperature not exceeding 30.Redissolve the residue in 1.0mLof a mixture of methanol and water (50:50).

Standard preparation— Dissolve USP Ranitidine Hydrochloride RSin a mixture of methanol and water (50:50)to obtain a solution having a known concentration of 448µg (equivalent to 400µg of ranitidine)per mL.Dilute portions of this Standard preparationquantitatively with the mixture of methanol and water (50:50)to obtain solutions having concentrations of 224µg per mL(Diluted standard preparation A),112µg per mL(Diluted standard preparation B),56µg per mL(Diluted standard preparation C),22µg per mL(Diluted standard preparation D),and 11µg per mL(Diluted standard preparation E),respectively.

Resolution preparation— Dissolve USP Ranitidine Related Compound A RSin methanol to obtain a solution having a known concentration of 1.27mg per mL.

Procedure— Apply separately 10µLof the Standard preparation,the Diluted standard preparations(A,B,C,D,and E),and 20µL(superposition of 2×10µL)of the Test preparationto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.In addition,apply separately a further loading of 10µLof the Test preparationto the same plate,and on top of this application,apply 10µLof the Resolution preparation.Perform the chromatography as described in Chromatographic purityunder Ranitidine Hydrochloride.Examine the plate and compare the intensities of any secondary spots observed in the chromatogram of the Test preparationwith those of the principal spots in the chromatograms of the Standard preparationand Diluted standard preparations(A,B,C,D,and E):the system suitability requirements are met when there is complete resolution between the primary spots of the Test preparationand the Resolution preparationand if a spot is observed in the chromatogram of Diluted standard preparation E.The major secondary spot is not greater in size or intensity than the principal spot produced by the Standard preparation(2.0%),and no other secondary spot is greater in size or intensity than the principal spot produced by Diluted standard preparation A(1.0%).The sum of the intensities of all secondary spots obtained from the Test preparationcorresponds to not more than 5.0%.[NOTE—Spots established as arising from other components in the formulation are to be ignored.]

Mobile phase,Standard preparation,System suitability solution,andChromatographic system— Prepare as directed in the Assayunder Ranitidine Hydrochloride,the chromatographic column being fitted with a suitable pre-column also containing packing L1.

Assay preparation— Dilute an accurately measured quantity of Oral Solution,quantitatively,and stepwise if necessary,with Mobile phaseto obtain a solution having a concentration of 0.1mg of ranitidine per mL.

Procedure— Separately inject an equal quantity (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the area responses for the major peaks.Calculate the quantity,in mg,of C13H22N4O3Sin the portion of Oral Solution taken by the formula: in which 314.40and 350.87are the molecular weights of ranitidine and ranitidine hydrochloride respectively;Lis the labeled quantity of ranitidine in the Oral Solution taken;Dis the concentration,in mg per mL,of ranitidine in the Assay preparation,on the basis of the labeled quantity and the extent of dilution;Cis the concentration,in mg per mL,of USP Ranitidine Hydrochloride RSin the Standard preparation;and rUand rSare the peak area responses obtained from the Assay preparationand the Standard preparation,respectively.