Identification—
The retention times of the major peaks in the chromatogram of the
Assay preparationcorrespond to those of the
Standard preparationobtained as directed in the
Assay.
Dissolution,Procedure for a Pooled Sample á711ñ—
[NOTE—Protect solutions from light throughout this test.
]
Medium:
0.1Nhydrochloric acid;900mL.
Apparatus 2:
50rpm.
Time:
30minutes.
Procedure—
Determine the amounts of C
17H
27NO
4and C
15H
14F
3N
3O
4S
2dissolved,employing the procedure set forth in the
Assay,using filtered portions of the solution under test,suitably diluted with
Medium,if necessary,in comparison with a Standard solution having known concentrations of
USP Nadolol RSand
USP Bendroflumethiazide RS,prepared by dissolving them in the minimal amount of methanol and diluting to the desired concentrations with
Medium.
Tolerances—
Not less than 80%(Q)of the labeled amounts of nadolol (C17H27NO4)and bendroflumethiazide (C15H14F3N3O4S2)are dissolved in 30minutes.
Assay—
[NOTE—Use low-actinic glassware for the
Assay preparationand the
Standard preparation.
]
Mobile phase—
Dissolve 5.62g of sodium chloride and 1.97g of anhydrous sodium acetate in 1000mLof water in a 2-liter volumetric flask.Add 4.0mLof glacial acetic acid and 800mLof methanol,dilute with water to volume,mix,filter,and degas.Make adjustments,if necessary (see
System Suitabilityunder
Chromatography á621ñ).
Standard preparation—
Dissolve accurately weighed quantities of
USP Nadolol RSand
USP Bendroflumethiazide RSin methanol and dilute quantitatively,and stepwise if necessary,with methanol to obtain a solution having known concentrations of about 0.4mg of
USP Nadolol RSper mLand about 0.4
Jmg of
USP Bendroflumethiazide RSper mL,
Jbeing the ratio of the labeled amount,in mg,of bendroflumethiazide to the labeled amount,in mg,of nadolol per Tablet.
Assay preparation—
Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 40mg of nadolol,to a 100-mLvolumetric flask,add methanol and sonicate for 15minutes with occasional shaking.Dilute with methanol to volume,mix,and centrifuge.
Chromatographic system
(see
Chromatography á621ñ)—The liquid chromatograph is equipped with a 270-nm detector and a 4.6-mm ×30-cm column that contains packing L11.The flow rate is about 1.5mLper minute.Chromatograph the
System suitability preparationand the
Standard preparation,and record the peak responses as directed under
Procedure:the resolution,
R,between the solvent and 2,4-disulfamyl-5-trifluoromethylaniline peaks is not less than 1.4,the resolution,
R,between the 2,4-disulfamyl-5-trifluoromethylaniline and nadolol peaks is not less than 1.4,and the resolution,
R,between the nadolol and bendroflumethiazide peaks is not less than 1.7.The relative standard deviation for replicate injections of the
Standard preparationis not more than 3.0%.
Procedure—
Separately inject equal volumes (about 20µL)of the
Standard preparationand the
Assay preparationinto the chromatograph,record the chromatograms,and measure the responses of the major peaks.The relative retention times are about 0.3for nadolol and 1.0for bendroflumethiazide.Calculate the quantity,in mg,of nadolol (C
17H
27NO
4)in the portion of Tablets taken by the formula:
100C(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Nadolol RSin the
Standard preparation,and
rUand
rSare the peak responses of nadolol obtained from the
Assay preparationand the
Standard preparation,respectively.Calculate the quantity,in mg,of bendroflumethiazide (C
15H
14F
3N
3O
4S
2)in the portion of Tablets taken by the same formula,changing the terms to refer to bendroflumethiazide.