Chromatographic purity—
Diluent, Mobile phase, System suitability solution, and Chromatographic system—
Proceed as directed in the Assay.
Standard solution—
Prepare as directed for Standard preparation in the Assay.
Test solution—
Prepare as directed for Assay preparation in the Assay.
Procedure—
Inject a volume (about 10 µL) of the
Test solution into the chromatograph, record the chromatogram, and measure the peak areas. Calculate the percentage of total impurities in the portion of Bisoprolol Fumarate taken by the formula:
100(ri / rs),
in which
ri is the sum of areas for all the peaks, excluding the fumaric acid and bisoprolol peaks; and
rs is the sum of the areas of all the peaks in the chromatogram: not more than 0.5% of total impurities is found.
Content of fumaric acid—
Transfer about 500 mg of Bisoprolol Fumarate, accurately weighed, to a beaker, and dissolve in 70 mL of dehydrated alcohol. Add 8.0 mL of 0.1 N tetrabutylammonium hydroxide VS, and stir for 2 minutes. Titrate with 0.1 N tetrabutylammonium hydroxide VS, determining the endpoint potentiometrically, using a glass-calomel electrode system. Perform a blank determination, and make any necessary correction (see
Titrimetry 
541
). Each mL of 0.1 N tetrabutylammonium hydroxide is equivalent to 5.804 mg of fumaric acid: not less than 14.8% and not more than 15.4% of fumaric acid is found, calculated on the anhydrous basis.
Assay—
Diluent—
Prepare a mixture of water and acetonitrile (65:35).
Mobile phase—
To a 1-L portion of
Diluent add 5 mL of heptafluorobutyric acid, 5 mL of diethylamine, and 2.5 mL of formic acid. Mix, filter, and degas. Make adjustments if necessary (see
System Suitability under
Chromatography 621).
System suitability solution—
Prepare a solution in Diluent containing about 0.5 mg of propranolol hydrochloride and 1 mg of Bisoprolol Fumarate per mL.
Standard preparation—
Quantitatively dissolve an accurately weighed quantity of
USP Bisoprolol Fumarate RS in
Diluent to obtain a solution having a known concentration of about 1 mg per mL.
Assay preparation—
Transfer about 50 mg of Bisoprolol Fumarate, accurately weighed, to a 50-mL volumetric flask. Dissolve in and dilute with Diluent to volume, and mix.
Chromatographic system (see Chromatography 621)—
The liquid chromatograph is equipped with a 273-nm detector and a 4.6-mm × 12.5-cm column that contains packing L7. The flow rate is about 1 mL per minute. Chromatograph the
System suitability solution, and record the peak areas as directed for
Procedure: the resolution,
R, between bisoprolol and propranolol is not less than 7.0. Chromatograph the
Standard preparation, and record the peak areas 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 2.0%.
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
18H
31NO
4)
2·C
4H
4O
4 in the portion of Bisoprolol Fumarate taken by the formula:
50C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Bisoprolol Fumarate RS in the
Standard preparation; and
rU and
rS are the peak areas obtained from the
Assay preparation and the
Standard preparation, respectively.
;)
-(2-Isoproproxyethoxy)-p-tolyl]oxy]-3-(isopropylamino)-2-propanol fumarate (2:1) (salt)
2
and +2