Medium: water;500mL.

Apparatus 2: 100rpm.

Time: 60minutes.

Procedure— Determine the amount of isopropamide (C23H33N2O)dissolved from UVabsorbances at the wavelength of maximum absorbance at about 258nm of filtered portions of the solution under test,suitably diluted with Medium,if necessary,in comparison with a Standard solution having a known concentration of USP Isopropamide Iodide RSin the same medium.

Tolerances— Not less than 70%(Q)of the labeled amount of C23H33N2Ois dissolved in 60minutes.

Procedure for content uniformity— Crush and transfer 1Tablet to a 100-mLvolumetric flask with the aid of about 50mLof water,and shake by mechanical means for 30minutes.Dilute with water to volume,mix,and filter,discarding the first 20mLof the filtrate.Concomitantly determine the absorbances of this solution and a Standard solution of USP Isopropamide Iodide RSin the same medium having a known concentration of about 70µg per mL,in 5-cm cells at 280nm and at the wavelength of maximum absorbance at about 258nm,with a suitable spectrophotometer,using water as the blank.Calculate the quantity,in mg,of isopropamide (C23H33N2O)in the Tablet taken by the formula: in which 353.53and 480.43are the molecular weights of isopropamide and isopropamide iodide,respectively,Tis the labeled quantity,in mg,of isopropamide in the Tablet,Cis the concentration,in µg per mL,of USP Isopropamide Iodide RSin the Standard solution,Dis the concentration,in µg per mL,of isopropamide in the test solution,based upon the labeled quantity per Tablet and the extent of dilution,and AUand ASare the absorbances of the test solution and the Standard solution,respectively,at the wavelengths indicated by the subscripts.

Ion-exchange column— Insert a small pledget of glass wool in the bottom of a 6-mm ×240-mm glass tube fitted with a stopcock,fill the tube with water,and add an aqueous slurry of a suitable anion-exchange resin,chloride form (soaked in water for not less than 24hours prior to use),until a height of about 200mm is reached.Wash the column with 50mLof water,and use without delay.

Standard preparation— Transfer about 135mg of USP Isopropamide Iodide RS,accurately weighed,to a 250-mLvolumetric flask,and dissolve in 150mLof water.Add 5mLof aluminum chloride solution (1in 10)and 2mLof ammonium hydroxide,then dilute with water to volume,mix,and filter,discarding the first 15mLof the filtrate.Use the subsequent filtrate as directed for Procedure.

Assay preparation— Weigh and finely powder not less than 25Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 100mg of isopropamide,to a 250-mLvolumetric flask,add 150mLof water,and shake by mechanical means for 60minutes.Add 5mLof aluminum chloride solution (1in 10)and 2mLof ammonium hydroxide,dilute with water to volume,mix,and filter,discarding the first 15mLof the filtrate.Use the subsequent filtrate as directed for Procedure.

Procedure— Pipet 50.0mLeach of the Standard preparationand the Assay preparation,respectively,onto separate ion-exchange columns,and collect the eluates in separate 200-mLvolumetric flasks.Regulate the flow of effluent so that it does not exceed 40drops per minute,and when the liquid level reaches the top of each column,add successively two 5-mLportions and one 10-mLportion of water to each column,allowing each portion just to enter the column before adding the next portion of water.After the eluates have been collected,dilute the contents of each flask with water to volume,and mix.Concomitantly determine the absorbances of the solutions in 5-cm cells at 280nm and at the maximum at about 258nm,with a suitable spectrophotometer,using water as the blank.Calculate the quantity,in mg,of isopropamide (C23H33N2O)in the portion of Tablets taken by the formula: in which 353.53and 480.43are the molecular weights of isopropamide and isopropamide iodide,respectively,Cis the concentration,in µg per mL,of USP Isopropamide Iodide RSin the Standard preparation,and AUand ASare the absorbances of the solutions from the Assay preparationand the Standard preparation,respectively,at the wavelengths indicated by the subscripts.