Cell: 1mm.

Solution— Place the contents of Capsules,equivalent to about 200mg of amantadine hydrochloride,in a vessel,dissolve in 0.1Nhydrochloric acid,and filter.Transfer the filtrate to a separator,add 1mLof 5Nsodium hydroxide,and extract with 5mLof methylene chloride.Filter the extract through anhydrous sodium sulfate,and rinse the anhydrous sodium sulfate with 2mLof methylene chloride.

Medium: water;900mL.

Apparatus 1: 100rpm.

Time: 45minutes.

Internal standard solution— Dissolve an accurately weighed quantity of naphthalene in hexane to obtain a solution having a known concentration of about 0.054mg per mL.

Standard solution— Dissolve an accurately weighed quantity of USP Amantadine Hydrochloride RSin water to obtain a solution having a known concentration of about 0.1mg per mL.Pipet 15.0mLof this solution into a 50-mLscrew-capped test tube,add 5.0mLof 5Nsodium hydroxide and 10.0mLof Internal standard solution,and shake for 60minutes.Collect the hexane layer.

Test solution— Filter 15.0mLof the solution under test and place into a 50-mLscrew-capped test tube.Pipet 5.0mLof 5Nsodium hydroxide and 10.0mLof the Internal standard solutioninto the test tube,and shake for 60minutes.Collect the hexane layer (Test solution).

Chromatographic system— Proceed as directed under the Assay.

Procedure— Separately inject equal volumes (about 2.5µL)of the Standard solutionand the Test solution.Record the chromatograms,and measure the responses for the major peaks.Calculate the amount of C10H17N·HCl dissolved.

Tolerances— Not less than 75%(Q)of the labeled amount of C10H17N·HCl is dissolved in 45minutes.

Internal standard solution— Dissolve a quantity of naphthalene in hexane to obtain a solution having a concentration of about 0.4mg per mL.

Standard preparation— Transfer about 200mg,accurately weighed,of USP Amantadine Hydrochloride RSto a 100-mLvolumetric flask,dissolve in and dilute with water to volume,and mix.Pipet 25.0mLof this solution into a 250-mLseparator,add 25mLof 2.0Nsodium hydroxide and 50.0mLof Internal standard solution.Shake for 60minutes,and collect the hexane layer (Standard preparation).

Assay preparation— Transfer not fewer than 20Capsules to a 200-mLvolumetric flask.Add 40mLof 0.1Nhydrochloric acid,and heat gently to achieve complete dissolution.Cool,and dilute with water to volume.Pipet 5.0mLof the solution into a 250-mLseparator,and add 40mLof 1.0Nsodium hydroxide and 50.0mLof Internal standard solution.Shake for 60minutes,and collect the hexane layer (Assay preparation).

Chromatographic system (see Chromatography á621ñ)—The gas chromatograph is equipped with a flame-ionization detector and a 2-mm ×1.22-m glass column packed with 10%phase G1on 100-to 120-mesh support S1A.The column is maintained at about 115,and the injection port and detector block are maintained at about 250.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the resolution,R,between napthalene and amantadine is not less than 2,the tailing factor for the analyte peak is not more than 2.0,and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 1µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for all of the peaks.Calculate the quantity,in mg,of amantadine hydrochloride (C10H17N·HCl)in the portion of Capsules taken by the formula: in which Cis the concentration,in mg per mL,of USP Amantadine Hydrochloride RSin the Standard preparation;and RUand RSare the peak response ratios obtained from the Assay preparationand the Standard preparation,respectively.