Medium: 0.01Nhydrochloric acid;900mL.

Apparatus 2: 50rpm.

Time: 45minutes.

Procedure— Determine the amount of C15H14F3N3O4S2dissolved by employing UVabsorption at the wavelength of maximum absorbance at about 271nm on filtered portions of the solution under test,suitably diluted with water,if necessary,in comparison with a Standard solution having a known concentration of USP Bendroflumethiazide RSin the same Medium.

Tolerances— Not less than 75%(Q)of the labeled amount of C15H14F3N3O4S2is dissolved in 45minutes.

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.

Standard preparation— Dissolve an accurately weighed quantity of USP Bendroflumethiazide RSin methanol,and dilute quantitatively and stepwise with methanol to obtain a solution having a known concentration of about 50µg per mL.

Assay preparation— Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 5mg of bendroflumethiazide,to a 100-mLvolumetric flask,add about 70mLof methanol,and sonicate for 15minutes,with occasional shaking.Dilute with methanol to volume,mix,and centrifuge a portion of the solution for 15minutes.

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 L11maintained at a temperature of 35±5.The flow rate is about 1.5mLper minute.Chromatograph five replicate injections of the Standard preparation,and record the peak responses as directed for Procedure:the relative standard deviation is not more than 3.0%,and the tailing factor is not more than 2.0.

Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the response of the major peak.Calculate the quantity,in mg,of C15H14F3N3O4S2in the portion of Tablets taken by the formula: in which Cis the concentration,in µg per mL,of USP Bendroflumethiazide RSin the Standard preparation,and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.