A:Thin-Layer Chromatographic Identification Test á201ñ—

B: 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.

Mobile phase— Prepare a mixture of 15mmol of sodium dodecyl sulfate in a mixture of water and acetonitrile (1:1).Adjust with phosphoric acid to a pHof 2.6±0.1,filter,and degas.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Diluent— Prepare a mixture of Mobile phase and water (2:1).

System suitability solution 1— Dissolve an accurately weighed quantity of USP Loratadine RS,and dilute quantitatively,and stepwise if necessary,to obtain a solution having a known concentration of about 0.002mg per mL.

System suitability solution 2— Quantitatively transfer 5.0mLof System suitability solution 1into a suitable container,dilute with Diluentto 50mL,and mix.

Resolution solution— Transfer an amount of Oral Solution,equivalent to 20mg of loratadine,into a screw-cap glass container.Add 1mLof 3%aqueous hydrogen peroxide,and mix.Cap,and heat at 65for 18to 24hours.

Test solution— Transfer an accurately measured volume of Oral Solution,equivalent to about 5mg of loratadine,to a 25-mLvolumetric flask,dilute with Diluentto volume,and mix.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm ×25-cm column that contains 5-µm packing L7.The flow rate is about 2mLper minute.The column temperature is maintained between 30and 40.Chromatograph the Resolution solution,and record the peak areas as directed for Procedure:the relative retention times are about 0.70for ethyl 4-[8-chloro-5,6-dihydro-4-(hydroxymethyl)-11H-benzo[5,6]cyclohepta[1,2-b]pyridin-11-ylidene]-1-piperidinecarboxylate,0.84for ethyl 4-[8-chloro-5,6-dihydro-2-(hydroxymethyl)-11H-benzo[5,6]cyclohepta[1,2-b]pyridin-11-ylidene]-1-piperidinecarboxylate,and 1.0for loratadine;and the resolution,R,between loratadine and ethyl 4-[8-chloro-5,6-dihydro-2-(hydroxymethyl)-11H-benzo[5,6]cyclohepta[1,2-b]pyridin-11-ylidene]-1-piperidinecarboxylate is not less than 3.0.Chromatograph System suitability solution 1,and record the peak area response of the loratadine peak as directed for Procedure:the tailing factor is not less than 0.7and not greater than 1.1.Chromatograph System suitability solution 2,and record the peak area response of the loratadine peak as directed for Procedure:the relative standard deviation for replicate injections of System suitability solution 2is not more than 10%.

Procedure— Inject about 50µLof the Test solutioninto the chromatograph,record the chromatogram,and measure all the peak area responses.Calculate the percentage of each individual related compound in the portion of Oral Solution taken by the formula: in which riis the individual peak response of each related compound in the Test solution;and rsis sum of the responses of all the peaks,excluding excipient peaks:not more than 0.3%of ethyl 4-[8-chloro-5,6-dihydro-4-(hydroxymethyl)-11H-benzo[5,6]cyclohepta[1,2-b]pyridin-11-ylidene]-1-piperidinecarboxylate is found;not more than 0.3%of ethyl 4-[8-chloro-5,6-dihydro-2-(hydroxymethyl)-11H-benzo[5,6]cyclohepta[1,2-b]pyridin-11-ylidene]-1-piperidinecarboxylate is found;not more than 0.2%of any other individual impurity is found;and the sum of all impurities is not more than 0.5%.

0.05M Monobasic potassium phosphate solution— Transfer about 6.8g of monobasic potassium phosphate,accurately weighed,to a 1-Lvolumetric flask,dissolve in and dilute with water to volume,and mix.Adjust with phosphoric acid to a pHof 3.0±0.1.

Mobile phase— Prepare a filtered and degassed mixture of 0.05M Monobasic potassium phosphate solutionand acetonitrile (7:3).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Internal standard preparation— Dissolve an accurately weighed quantity of butylparaben in a mixture of water and acetonitrile (7:3),and dilute quantitatively,and stepwise if necessary,with a mixture of water and acetonitrile (7:3)to obtain a solution having a concentration of about 0.3mg per mL.

Standard stock peparation— Dissolve an accurately weighed quantity of USP Loratadine RSin acetonitrile,and dilute quantitatively,and stepwise if necessary,with acetonitrile to obtain a solution having a known concentration of about 1.0mg per mL.

Standard preparation— Transfer 5.0mLof Internal standard preparation,5.0mLof Standard stock preparation,and 12mLof water into a 50-mLvolumetric flask.Dilute with a mixture of water and acetonitrile (7:3),and mix.

Assay preparation— Transfer an accurately measured quantity of Oral Solution,equivalent to 5mg of loratadine,into a 50-mLvolumetric flask.Pipet 5.0mLof Internal standard preparationinto the flask,dilute with a mixture of water and acetonitrile (7:3)to volume,and mix.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 254-nm detector and a 4-mm ×30-cm column that contains 5-µm packing L11.The flow rate is about 2mLper minute.The column temperature is maintained between 20and 30.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the relative retention times are about 0.78for butylparaben and 1.0for loratadine;the resolution,R,between loratadine and butylparaben is not less than 1.9;the tailing factor is not more than 1.6for the loratadine and butylparaben peaks;and the relative standard deviation for replicate injections is not more than 2%.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg of loratadine (C22H23ClN2O2)in the portion of Oral Solution taken by the formula: in which Cis the concentration,in mg per mL,of USP Loratadine RSin the Standard preparation;and RUand RSare the ratios of loratadine to the internal standard peak responses obtained from the Assay preparationand the Standard preparation,respectively.