A: Infrared Absorption á197Kñ.

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.

0.05M Triethylamine solution,Mobile phase,System suitability solution,and Chromatographic system— Proceed as directed in the Assay.

Standard stock solution— Use the Standard stock preparationas prepared in the Assay.

Standard solution— Dilute 1.0mLof the Standard stock solutionquantitatively,and stepwise if necessary,with Mobile phaseto obtain a solution having a known concentration of about 0.001mg per mL.

Test solution— Use the Assay stock preparation.

Procedure— Separately inject equal volumes (about 10µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms for not less than 20minutes,and measure all of the peak areas.The area of any single peak obtained from the Test solutionis not greater than the area of the tacrine hydrochloride peak obtained from the chromatogram of the Standard solution:not more than 0.1%of any individual impurity is found;and not more than 0.2%of total impurities is found.

0.05M Triethylamine solution— Dissolve 13.8mLof triethylamine in 1900mLof water.Adjust with formic acid to a pHof 3.0,dilute with water to 2000mL,and mix.

Mobile phase— Prepare a filtered and degassed mixture of 0.05M Triethylamine solutionand acetonitrile (87:13).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

System suitability solution— Dissolve suitable quantities of USP Tacrine Hydrochloride RSand 2-aminobenzonitrile in Mobile phaseto obtain a solution containing about 100µg per mLand 25µg per mL,respectively.

Standard stock preparation— Dissolve an accurately weighed quantity of USP Tacrine Hydrochloride RSin Mobile phaseto obtain a solution containing about 1mg per mL.

Standard preparation— Dilute 1.0mLof the Standard stock preparationwith Mobile phaseto obtain a solution having a known concentration of about 0.1mg per mL.

Assay stock preparation— Transfer about 100mg of Tacrine Hydrochloride,accurately weighed,to a 100-mLvolumetric flask,dissolve in and dilute with Mobile phaseto volume,and mix.

Assay preparation— Transfer 1.0mLof the Assay stock preparationto a 10-mLvolumetric flask,and dilute with Mobile phaseto volume to obtain a solution having a known concentration of about 0.1mg per mL.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 243-nm detector and a 4.6-mm ×25-cm column that contains 5-µm packing L11.The flow rate is about 1.5mLper minute.Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.48for 2-aminobenzonitrile and 1.0for tacrine hydrochloride;the resolution,R,between 2-aminobenzonitrile and tacrine hydrochloride is not less than 10.0;and the column efficiency is not less than 5200theoretical plates.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the relative standard deviation for replicate injections is not more than 0.41%.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the areas for the major peaks.Calculate the quantity,in mg,of C13H14N2·HCl·H2O,in the portion of Tacrine Hydrochloride taken by the formula: in which Cis the concentration,in mg per mL,of USP Tacrine Hydrochloride RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.