A: Thin-Layer Chromatographic Identification Test 201—

B: The retention times of the major peaks in the chromatograms of the Bisoprolol fumarate assay preparation and the Hydrochlorothiazide assay preparation correspond to those in the chromatogram of the Standard preparation, as obtained in the Assay.

Medium: 0.1 N hydrochloric acid; 900 mL.

Apparatus 2: 75 rpm.

Times: 20 minutes for bisoprolol fumarate; 30 minutes for hydrochlorothiazide.

Triethylamine solution— Mix 2 mL of triethylamine with 1000 mL of water, and adjust with phosphoric acid to a pH of 3.0.

Mobile phase— Prepare a filtered and degassed mixture of acetonitrile and Triethylamine solution (1:4). Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard stock solution 1— Quantitatively dissolve an accurately weighed quantity of USP Bisoprolol Fumarate RS in Medium to obtain a solution having a known concentration of about 0.5 mg per mL.

Standard stock solution 2— Transfer about 30 mg of USP Hydrochlorothiazide RS, accurately weighed, to a 50-mL volumetric flask, dissolve in 5 mL of methanol, dilute with Medium to volume, and mix.

Standard solution— Dilute accurately measured volumes of Standard stock solution 1 and Standard stock solution 2 with Medium to obtain a solution having known concentrations of bisoprolol fumarate and hydrochlorothiazide corresponding to those of the solution under test.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a UV detector capable of measuring peak responses at 227 nm and 272 nm, simultaneously, and a 3.9-mm × 15-cm column that contains packing L11. The flow rate is about 1.5 mL per minute. Chromatograph the Standard solution, and record the peak areas as directed for Procedure: the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 20 µL) of the Standard solution and the filtered portions of the solution under test into the chromatograph, record the chromatograms, and measure the peak areas for bisoprolol at 227 nm and for hydrochlorothiazide at 272 nm. Calculate the quantities, in mg, of bisoprolol fumarate (C18H31NO4)2·C4H4O4 and hydrochlorothiazide (C7H8ClN3O4S2) dissolved.

Tolerances— Not less than 80% (Q) of the labeled amount of (C18H31NO4)2·C4H4O4 is dissolved in 20 minutes and not less than 80% (Q) of the labeled amount of C7H8ClN3O4S2 is dissolved in 30 minutes.

Diluent, Solution A, Solution B, Mobile phase, and System suitability solution— Proceed as directed in the Assay.

Standard solution— Dissolve an accurately weighed quantity of USP Hydrochlorothiazide RS in Diluent, and quantitatively dilute with Diluent, if necessary, to obtain a solution having a known concentration of about 2 µg per mL.

Test stock solution— Proceed as directed for Assay stock preparation in the Assay.

Test solution— Quantitatively dilute an accurately measured volume of the Test stock solution with Diluent to obtain a solution having a concentration of about 100 µg of bisoprolol fumarate per mL.

Chromatographic system (see Chromatography 621)— Prepare as directed in the Assay, but use a 260-nm detector. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the resolution, R, between chlorothiazide and hydrochlorothiazide is not less than 1.5. Chromatograph the Standard solution, and record the peak responses as directed for Procedure: the tailing factor is not more than 1.3; 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 solution and the Test solution into the chromatograph, record the chromatograms, and measure the responses for all the peaks. Calculate the percentage of each impurity in the portion of Tablets taken by the formula: in which F is the response factor, equal to 1.2 for the peak with a relative retention time of 0.69 and 1.4 for the peak with a relative retention time of 1.2, both retention times relative to that of the hydrochlorothiazide peak; WB and WH are the labeled quantities, in mg, of bisoprolol fumarate and hydrochlorothiazide, respectively, in each Tablet; CS is the concentration, in mg per mL, of USP Hydrochlorothiazide RS in the Standard solution; CB is the concentration, in mg per mL, of bisoprolol fumarate in the Test solution; ri is the peak response of each of the two impurities obtained from the Test solution; and rS is the response for the hydrochlorothiazide peak obtained from the Standard solution: not more than 1.0% for the impurity with a relative retention time of 0.69 is found; and not more than 2.0% for the impurity with a relative retention time of 1.2 is found.

(Official January 1, 2007)

Diluent— Mix 10 mL of 1 M dibutylammonium phosphate with 1000 mL a mixture of water and acetronitrile.

Solution A— Mix 10 mL of 1 M dibutylammonium phosphate with 1000 mL of water.

Solution B— Prepare a mixture of acetonitrile and water (3:2). Add 10 mL of 1 M dibutylammonium phosphate per liter, stir vigorously for 2 minutes, 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).

System suitability solution— Prepare a solution of USP Chlorothiazide RS and USP Hydrochlorothiazide RS in Diluent containing 40 µg of each per mL.

Standard preparation— Dissolve suitable quantities of USP Bisoprolol Fumarate RS and USP Hydrochlorothiazide RS in Diluent to obtain a solution having known concentrations of about 100 µg of each per mL. Stir by mechanical means for 1 hour.

Assay stock preparation— Weigh 10 Tablets, and transfer to a 100-mL volumetric flask. Add about 50 mL of Diluent, sonicate for 10 minutes, and cool. Dilute with Diluent to volume, stir by mechanical means for 1 hour, and centrifuge.

Bisoprolol fumarate assay preparation— Quantitatively transfer a portion of the Assay stock preparation to a 50-mL volumetric flask, and dilute with Diluent to volume to obtain a solution having a concentration of about 100 µg of bisoprolol fumarate per mL.

Hydrochlorothiazide assay preparation— Quantitatively transfer a portion of the Assay stock preparation to a 50-mL volumetric flask, and dilute with Diluent to volume to obtain a solution having a concentration of about 62.5 µg of hydrochlorothiazide per mL.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with 225-nm detector and an 8-mm × 10-cm column that contains packing L11. The flow rate is about 3 mL per minute. The chromatograph is programmed as follows. Chromatograph the System suitability solution, and record the peak areas as directed for Procedure: the resolution, R, between chlorothiazide and hydrochlorothiazide is not less than 1.5. Chromatograph the Standard preparation, and record the peak areas as directed for Procedure: the tailing factor for the hydrochlorothiazide peak is not more than 1.3; 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, Bisoprolol fumarate assay preparation, and Hydrochlorothiazide assay preparation into the chromatograph, record the chromatograms, and measure the areas for the major peaks. Calculate the quantities, in mg, of bisoprolol fumarate (C18H31NO4)2·C4H4O4 and hydrochlorothiazide (C7H8ClN3O4S2) in the portion of Tablets taken by the formula: in which C is the concentration, in mg per mL, of USP Bisoprolol Fumarate RS or USP Hydrochlorothiazide RS in the Standard preparation, as appropriate; V is the volume of the Assay stock preparation used to prepare the Bisoprolol fumarate assay preparation or the Hydrochlorothiazide assay preparation; rU is the peak area obtained from the Bisoprolol fumarate assay preparation or the Hydrochlorothiazide assay preparation, as appropriate; and rS is the corresponding peak area obtained from the Standard preparation.