Change to read:
Dissolution 
711
—
Medium:
water; 900 mL.
Apparatus 2:
50 rpm.
Time:
30 minutes.
Mobile phase—
Prepare a filtered and degassed mixture of acetonitrile and 0.2% phosphoric acid (64:36). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Standard stock solution—
Accurately weigh about 20 mg of
USP Fosinopril Sodium RS into a 200-mL volumetric flask, dissolve in 6-mL of methanol, sonicate briefly, and dilute with
Medium to volume.
Standard solution—
Dilute the
Standard stock solution with
Medium as directed in the following table.
| Label claim |
Standard stock
solution (mL) |
Final volume
(Flask size) |
| 5 mg |
5.0 |
100 |
| 10 mg |
10 |
100 |
| 20 mg |
20 |
100 |
| 40 mg |
40 |
100 |
1S (USP31)
Test solution—
Use portions of the solution under test passed through a 1.2-µm acrylic filter. [Note—Do not use glass filters.]
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 215-nm detector and a 4.6-mm × 15-cm column, maintained at a temperature of 40
, that contains 5-µm packing L1. The flow rate is about 3 mL per minute. Chromatograph the
Resolution solution and the
Standard solution, and record the peak responses as directed for
Procedure: the resolution,
R, between fosinopril sodium and fosinopril related compound G is not less than 1.7; and the relative standard deviation for replicate injections of the
Standard solution is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 50 µL) of the
Test solution and the
Standard solution having a known concentration of
USP Fosinopril Sodium RS in the same
Medium, and record the chromatograms. Measure the responses for the major peaks, and calculate the amount of C
30H
45NNaO
7P dissolved.
Tolerances—
Not less than 80% (Q) of the labeled amount of C30H45NNaO7P is dissolved in 30 minutes.
Limit of related compound A—
Mobile phase, Diluent, and Chromatographic system—
Proceed as directed in the Assay.
Standard solution—
Dissolve an accurately weighed quantity of
USP Fosinopril Related Compound A RS in methanol to obtain a solution having a known concentration of about 0.1 mg per mL. Dilute with
Diluent to obtain a solution having a final known concentration of 0.0025 mg per mL.
Test solution—
Use the Assay preparation.
Procedure—
Separately inject equal volumes (about 50 µL) of the
Standard solution and the
Test solution into the chromatograph, record the chromatograms, and measure the peak responses for the major peaks. Calculate the percentage of fosinopril related compound A in the portion of Tablets taken by the formula:
1000C(rU / rS)
in which
C is the concentration, in mg per mL, of the fosinopril related compound A in the
Standard solution; and
rU and
rS are the peak responses obtained from the
Test solution and the
Standard solution, respectively. Not more than 4% is found.
Assay—
Mobile phase—
Prepare a degassed mixture of methanol and 0.2% phosphoric acid (78:22). Make adjustments if necessary (see
System Suitability under
Chromatography 621).
Diluent—
Prepare a mixture of 0.2 M urea solution and acetonitrile (80:20).
Standard preparation—
Dissolve an accurately weighed quantity of
USP Fosinopril Sodium RS to obtain a solution having a known concentration of about 0.1 mg per mL.
Assay preparation—
Transfer not fewer than 10 Tablets to a 500-mL volumetric flask, add 400 mL of Diluent, and stir for 40 minutes. Dilute with Diluent to volume, mix, and centrifuge. Quantitatively dilute an accurately measured volume (VS mL) of the clear supernatant with Diluent to obtain a solution ( VA mL) containing about 0.1 mg of fosinopril sodium per mL.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 215-nm detector and a 4.0-mm × 30-cm column that contains packing L1. The flow rate is about 2 mL per minute. Chromatograph the
Resolution solution and the
Standard preparation, and record the peak responses as directed for
Procedure: the relative retention time is 0.4 for fosinopril related compound A, and 1.0 for fosinopril sodium; the resolution,
R, between the fosinopril sodium and fosinopril related compound A peaks is not less than 2.0; and the relative standard deviation for replicate injections of the
Standard preparation 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. Continue the chromatography up to 1.5 times the retention time of the fosinopril sodium peak. Calculate the quantity, in mg, of fosinopril sodium (C
30H
45NNaO
7P) in the portion of Tablets taken by the formula:
50C(VA / VS)(rU / rS)
in which
C is the concentration, in mg per mL, of
USP Fosinopril Sodium RS in the
Standard preparation; VA is the volume, in mL, of the
Assay preparation; VS is the volume, in mL, of supernatant taken for the
Assay preparation; and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
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