Identification—
Dissolve about 10 mg of
USP Benztropine Mesylate RS in 50 mL of water in a separator to obtain a solution containing about 0.2 mg per mL. Transfer a portion of finely powdered Tablets, equivalent to about 10 mg of benztropine mesylate, to a suitable flask, add 50 mL of water, shake by mechanical means for 30 minutes, and filter into a second separator. Proceed as directed in the
Identification test under
Benztropine Mesylate Injection, beginning with “Separately add 2 mL of 1 N sodium hydroxide.”
Dissolution 
711
—
Medium:
0.1 N hydrochloric acid; 900 mL.
Apparatus 2:
50 rpm.
Time:
30 minutes.
Determine the amount of C21H25NO·CH4O3S dissolved by employing the following method.
Octylamine buffer—
Proceed as directed in the Assay.
Mobile phase—
Prepare a filtered and degassed mixture of acetonitrile and
Octylamine buffer (13:7). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Test solution—
Use a filtered portion of the solution under test from the dissolution vessel.
Standard solution—
Dissolve an accurately weighed amount of
USP Benztropine Mesylate RS in
Dissolution Medium, and dilute quantitatively, and stepwise if necessary, with
Dissolution Medium to obtain a solution having a known concentration similar to that of the
Test solution.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 220-nm detector and a 4.6-mm × 25-cm column that contains packing L7. The flow rate is about 2 mL per minute. Chromatograph the
Standard solution, and record the peak responses as directed for
Procedure: the tailing factor is not more than 2.0; and the relative standard deviation for replicate injections is not more than 3.0%.
Procedure—
Separately inject equal volumes (about 300 µL) of the
Standard solution and a filtered portion of the solution under test into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C
21H
25NO·CH
4O
3S dissolved by the formula:
900C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Benztropine Mesylate RS in the
Standard solution; and
rU and
rS are the peak responses obtained from the solution under test and the
Standard solution, respectively.
Tolerances—
Not less than 80% (Q) of the labeled amount of C21H25NO·CH4O3S is dissolved in 30 minutes.
Assay—
Octylamine buffer—
Transfer about 0.83 mL of octylamine to a 1-L volumetric flask, dilute with water to volume, mix, and adjust with phosphoric acid to a pH of 3.0.
Diluting solution—
Prepare a mixture of water, isopropyl alcohol, and phosphoric acid (60:40:0.1).
Mobile phase—
Prepare a filtered and degassed mixture of
Octylamine buffer and acetonitrile (11:9). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Standard preparation—
Dissolve an accurately weighed quantity of
USP Benztropine Mesylate RS in
Diluting solution, and dilute quantitatively, and stepwise if necessary, with
Diluting solution to obtain a solution having a known concentration of about 0.04 mg per mL.
Assay preparation—
Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 10 mg of benztropine mesylate, to a 250-mL volumetric flask, and add 150 mL of Diluting solution. Mix by mechanical means for not less than 60 minutes, and dilute with Diluting solution to volume. Centrifuge a portion of this mixture, and filter the supernatant layer.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 259-nm detector and a 4.6-mm × 25-cm column that contains packing L7. The flow rate is about 0.7 mL per minute. Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the tailing factor is not more than 4.0; and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 50 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of benztropine mesylate (C
21H
25NO·CH
4O
3S) in the portion of Tablets taken by the formula:
250C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Benztropine Mesylate RS in the
Standard preparation; and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
