Medium: water;500mL.

Apparatus 1: 100rpm.

Time: 45minutes.

Procedure— Determine the amount of C16H19BrN2·C4H4O4dissolved from UVabsorbances at the wavelength of maximum absorbance at about 264nm of filtered portions of the solution under test,suitably diluted with 3Nhydrochloric acid,in comparison with a Standard solution having a known concentration of USP Brompheniramine Maleate RSin the same medium.

Tolerances— Not less than 75%(Q)of the labeled amount of C16H19BrN2·C4H4O4is dissolved in 45minutes.

Standard preparation— Dissolve an accurately weighed quantity of USP Brompheniramine Maleate RSin water,and dilute quantitatively with water to obtain a solution having a known concentration of about 160µg per mL.Transfer 25.0mLof this solution to a separator containing 25mLof water,mix,and proceed as directed under Assay preparation,beginning with “adjust with sodium hydroxide solution (1in 10)to a pHof 11.”The concentration of USP Brompheniramine Maleate RSin the Standard preparationis about 20µg per mL.

Assay preparation— Weigh and finely powder not fewer than 20Tablets.Weigh accurately a portion of the powder,equivalent to about 4mg of brompheniramine maleate,mix with 50mLof water for 10minutes,adjust with sodium hydroxide solution (1in 10)to a pHof 11,and cool to room temperature.Extract the mixture with two 75-mLportions of solvent hexane,and combine the extracts in a second separator.Extract the solvent hexane solution with three 50-mLportions of dilute hydrochloric acid (1in 120),combining the acid extracts in a 200-mLvolumetric flask.Add dilute hydrochloric acid (1in 120)to volume,and mix.

Procedure— Concomitantly determine the absorbances of the Assay preparationand the Standard preparation,in 1-cm cells at the wavelength of maximum absorbance at about 264nm,with a suitable spectrophotometer,using dilute hydrochloric acid (1in 120)as the blank.Calculate the quantity,in mg,of C16H19Br N2·C4H4O4in the portion of Tablets taken by the formula: in which Cis the concentration,in µg per mL,of USP Brompheniramine Maleate RSin the Standard preparation;and AUand ASare the absorbances of the Assay preparationand the Standard preparation,respectively.