Cell: 1mm.

Solution— Dissolve about 50mg in 10mLof 0.1Nhydrochloric acid,and filter.Transfer the filtrate to a suitable separator,add 1mLof 5Nsodium hydroxide,and extract with 5mLof methylene chloride.

Internal standard solution— Transfer about 500mg of adamantane,accurately weighed,to a 10-mLvolumetric flask,dissolve in and dilute with dichloromethane to volume,and mix.

Test solution— Transfer about 1.0g of Amantadine Hydrochloride,accurately weighed,to a separator.Add 20mLof 5.0Nsodium hydroxide and 18mLof dichloromethane,and shake for 10minutes.Remove the water layer,dry the organic layer by swirling with anhydrous sodium sulfate,and allow to stand for a few minutes to ensure that all remaining water has been removed.Filter,collect the filtrate in a 20-mLvolumetric flask,add 0.2mLof Internal standard solution,and dilute with dichloromethane to volume.

Standard solution— Transfer about 10mg of USP Amantadine Hydrochloride RS,accurately weighed,to a separator.Add 20mLof 5.0Nsodium hydroxide and 18mLof dichloromethane,and shake for 10minutes.Remove the water layer,dry the organic layer by swirling with anhydrous sodium sulfate,and allow to stand for a few minutes to ensure that all remaining water has been removed.Filter,collect the filtrate in a 20-mLvolumetric flask,add 0.2mLof Internal standard solution,and dilute with dichloromethane to volume.

Chromatographic system (see Chromatography á621ñ)— The gas chromatograph is equipped with a flame-ionization detector and a 0.53-mm ×30-m fused-silica column coated with 1.0-µm G27stationary phase.The carrier gas is helium,flowing at a rate of about 4mLper minute,and the split flow is about 200mLper minute with a split flow ratio of 50:1.Initially the temperature of the column is equilibrated at 70for 5minutes,then the temperature is increased linearly at a rate of 10per minute to 250,and maintained at 250for at least 17minutes.The injection port temperature is maintained at 220,and the detector temperature is maintained at 300.Chromatograph the Standard solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.7for adamantane and 1.0for amantadine hydrochloride;the resolution,R,between adamantane and amantadine hydrochloride is not less than 20,and the relative standard deviation for replicate injections determined from the peak response ratios of amantadine to adamantane is not more than 5.0%.

Procedure— Separately inject equal volumes (about 2µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure all of the peak responses.Calculate the percentage of each impurity in the portion of Amantadine Hydrochloride taken by the formula: in which Riis the peak response ratio of each impurity to adamantane obtained from the Test solution;RSis the peak response ratio of amantadine to adamantane obtained from the Standard solution;WSis the weight,in mg,of USP Amantadine Hydrochloride RStaken to prepare the Standard solution;and WUis the weight,in mg,of Amantadine Hydrochloride taken to prepare the Test solution:not more than 0.3%of any individual impurity is found;and not more than 1.0%of total impurities is found.