A:Infrared Absorption á197Kñ.

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

Test solution— Transfer 100mg of Rimantadine Hydrochloride to a 10-mLcentrifuge tube,add 2mLof 1Nsodium hydroxide,and mix.Add 2mLof chloroform,and mix on a vortex mixer for 1minute.Allow the layers to separate,and apply 10µLof the organic layer.

Standard solution— Proceed as directed for the Test solution,using USP Rimantadine Hydrochloride RSin place of the test specimen.

Eluant: a mixture of ethyl acetate,methanol,and ammonium hydroxide (80:10:4).

Procedure— Use a low-actinic glass tank.Dry the plate in a stream of hot air,then heat in an oven at 105for 30minutes.Allow the plate to cool to room temperature.

Visualization— Place the plate in an atmosphere of chlorine,prepared by mixing 1.5%potassium permanganate solution and diluted hydrochloric acid (1:1),for about 90minutes.Allow to air-dry for 60minutes,and follow with visualization technique 20.

Standard solution— Transfer 10µLof toluene to a 100-mLvolumetric flask,dilute with chloroform to volume,and mix.

Test solution— Transfer about 750mg of Rimantadine Hydrochloride,accurately weighed,to a 10-mLvolumetric flask,dilute with chloroform to volume,and mix.

Chromatographic system (see Chromatography á621ñ)— The gas chromatograph is equipped with a flame-ionization detector and a 2-mm ×2-m column that contains 80-to 100-mesh support S1A.The column temperature is maintained at about 200,and nitrogen is used as the carrier gas.The injection port and detector temperatures are maintained at about 250.Chromatograph the Standard solution,and record the peak responses as directed for Procedure:the tailing factor is not more than 1.5for toluene;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 5µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms for 9minutes,and measure the responses for the toluene peaks.Calculate the percentage of toluene in the portion of Rimantadine Hydrochloride taken by the formula: in which 0.867is the specific gravity of toluene;WUis the weight,in mg,of Rimantadine Hydrochloride taken to prepare the Test solution;and rUand rSare the toluene peak responses obtained from the Test solutionand the Standard solution,respectively:not more than 0.1%is found.

Internal standard solution— Transfer about 400mg of n-eicosane to a 250-mLvolumetric flask,dilute with hexane to volume,and mix.

Standard preparation— Transfer about 40mg of USP Rimantadine Hydrochloride RS,accurately weighed,to a 50-mLcentrifuge tube,add 15mLof 1Nsodium hydroxide,and mix.Add 25.0mLof Internal standard solution,and shake by mechanical means for about 15minutes.Allow the layers to separate,and filter a portion of the top hexane layer through anhydrous sodium sulfate.Use the clear filtrate.

Assay preparation— Using about 40mg of Rimantadine Hydrochloride,accurately weighed,proceed as directed for Standard preparation.

Chromatographic system (see Chromatography á621ñ)— The gas chromatograph is equipped with a flame-ionization detector and a 4-mm ×1.8-m glass column that is packed with 3%phase G19on 100-to 200-mesh support S1A.The column temperature is maintained at about 160,and the injection port and detector temperatures are maintained at about 250.Nitrogen is used as the carrier gas.Adjust the carrier flow rate and temperature so that the n-eicosane elutes at about 8minutes.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the tailing factor is not more than 2.0for rimantadine;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 2µL)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 C12H21N·HCl in the portion of Rimantadine Hydrochloride taken by the formula: in which Cis the concentration,in mg per mL,of USP Rimantadine Hydrochloride in the Standard preparation;and RUand RSare the ratios of the rimantadine peak response to the n-eicosane peak response obtained from the Assay preparationand the Standard preparation,respectively.