A: Infrared Absorption 197K.

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

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

Standard stock solution— Use the Standard stock preparation as prepared in the Assay.

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

Test solution— Use the Assay stock preparation.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms for not less than 20 minutes, and measure all of the peak areas. The area of any single peak obtained from the Test solution is 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.

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

Mobile phase— Prepare a filtered and degassed mixture of 0.05 M Triethylamine solution and acetonitrile (87:13). Make adjustments if necessary (see System Suitability under Chromatography 621).

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

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

Standard preparation— Dilute 1.0 mL of the Standard stock preparation with Mobile phase to obtain a solution having a known concentration of about 0.1 mg per mL.

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

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

Chromatographic system (see Chromatography 621)— 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 1.5 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the relative retention times are about 0.48 for 2-aminobenzonitrile and 1.0 for 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 5200 theoretical 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 10 µL) of the Standard preparation and the Assay preparation into 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 C is the concentration, in mg per mL, of USP Tacrine Hydrochloride RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.