Chromatographic purity—
Buffer solution, Solution A, Solution B, and Mobile phase—
Proceed as directed in the Assay.
Standard solution—
Prepare as directed for the Standard preparation in the Assay.
Diluted standard solution—
Dilute 5 µL of the Standard solution with Solution A to 10.0 mL.
Test solution—
Prepare as directed for the Assay preparation.
Scopolamine hydrobromide solution—
Dissolve an accurately weighed quantity of
USP Scopolamine Hydrobromide RS in
Solution A to obtain a solution having a known concentration of about 0.05 mg per mL.
System suitability solution—
Dissolve about 50 mg of USP Methscopolamine Bromide RS in Solution A, add 1.0 mL of Scopolamine hydrobromide solution, and dilute with Solution A to 50.0 mL. This solution contains about 0.1% of scopolamine hydrobromide.
Chromatographic system (see Chromatography 
621
)—
Proceed as directed in the
Assay. In addition, chromatograph the
System suitability solution, and record the peak responses as directed for
Procedure: the resolution,
R, between methscopolamine and scopolamine is not less than 1.5; and the tailing factor for the methscopolamine peak is not more than 2.0.
Procedure—
Separately inject equal volumes (about 5 µL) of the
Diluted standard solution and the
Test solution into the chromatograph, record the chromatogram for four times the retention time of methscopolamine, and measure the responses for the major peaks. Disregard any peak with an area less than that of the methscopolamine peak in the chromatogram obtained from the
Diluted standard solution, and disregard any peak that is due to
Solution A. Calculate the percentage of each impurity in the portion of Methscopolamine Bromide taken by the formula:
100F(ri / rS)
in which
F is the relative response factor for the methscopolamine bromide impurities (see
Table 1);
ri is the peak area of any impurity obtained from the
Test solution; and
rS is the peak area of methscopolamine obtained from the chromatogram of the
Test solution: not more than 0.1% of any individual impurity is found; and not more than 0.5% of total impurities is found.
Table 1
| Name |
Relative
Retention
Time |
Relative
Response
Factor (F) |
| Tropic acid |
0.4 |
0.4 |
Scopolamine
hydrobromide |
0.9 |
1.0 |
Methylatropine
bromide |
1.2 |
1.0 |
Apomethscopolamine
bromide |
3.5 |
0.6 |
| Any other impurity |
— |
1.0 |
Assay—
Buffer solution—
Prepare a solution containing 5.16 g of sodium 1-hexanesulfonate monohydrate and 3.40 g of monobasic potassium phosphate in 1000 mL of water, adjust with 1 M phosphoric acid to a pH of 2.8, and mix.
Solution A—
Mix 850 mL of Buffer solution and 150 mL of acetonitrile, filter, and degas.
Solution B—
Mix 500 mL of Buffer solution and 500 mL of acetonitrile, filter, and degas.
Mobile phase—
Use variable mixtures of
Solution A and
Solution B as directed for
Chromatographic system. Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Standard preparation—
Dissolve an accurately weighed quantity of USP Methscopolamine Bromide RS in Solution A to obtain a solution having a known concentration of about 1.0 mg per mL.
Assay preparation—
Transfer about 50 mg of Methscopolamine Bromide, accurately weighed, to a 50-mL volumetric flask, dissolve in and dilute with Solution A to volume, and mix.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 210-nm detector and a 4.6-mm × 10-cm column that contains packing L1. The flow rate is about 3 mL per minute. The column temperature is maintained at 50
. The chromatograph is programmed as follows.
Time
(minutes) |
Solution A
(%) |
Solution B
(%) |
Elution |
| 0–3 |
100 |
0 |
isocratic |
| 3–10 |
100®85 |
0®15 |
linear gradient |
| 10–10.1 |
85®100 |
15®0 |
linear gradient |
| 10.1–13 |
100 |
0 |
re-equilibration |
Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the relative standard deviation for six replicate injections is not greater than 1%.
Procedure—
Separately inject equal volumes (about 5 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the peak area responses. Calculate the quantity, in mg, of C
18H
24BrNO
4 in the portion of Methscopolamine Bromide taken by the formula:
50C(rU / rS)
in which
C is the concentration, in mg per mL, of
USP Methscopolamine Bromide RS in the
Standard preparation; and
rU and
rS are the peak area responses of methscopolamine obtained from the
Assay preparation and the
Standard preparation, respectively.
USP29
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