Chromatographic purity
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.
Content of chloride
Transfer about 150 mg of Tacrine Hydrochloride, accurately weighed, to a 100-mL beaker. Dissolve in 40 mL of methanol and 10 mL of water, and acidify with 1 mL of nitric acid. Titrate with 0.1 N silver nitrate VS, determining the endpoint potentiometrically, using suitable electrodes (see
Titrimetry 541). Each mL of 0.1 N silver nitrate is equivalent to 3.545 mg of chloride. Not less than 13.6% and not more than 14.4% is found.
Assay
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 C
13H
14N
2·HCl·H
2O, in the portion of Tacrine Hydrochloride taken by the formula:
1000C(rU / rS),
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.