Medium: 0.1Nhydrochloric acid;900mL.

Apparatus 2: 50rpm.

Time: 60minutes.

Procedure— Determine the amount of C18H22N2·HCl dissolved by employing UVabsorption at the wavelength of maximum absorbance at about 251nm on filtered portions of the solution under test,suitably diluted with Dissolution Medium,if necessary,in comparison with a Standard solution having a known concentration of USP Desipramine Hydrochloride RSin the same Medium.

Tolerances— Not less than 75%(Q)of the labeled amount of C18H22N2·HCl is dissolved in 60minutes.

Procedure for content uniformity— Transfer 1finely powdered Tablet to a 100-mLvolumetric flask,add 50mLof 0.1Nhydrochloric acid,and shake by mechanical means for 15minutes.Dilute with 0.1Nhydrochloric acid to volume,mix,and filter,discarding the first 20mLof the filtrate.Dilute a portion of the subsequent filtrate quantitatively and stepwise with 0.1Nhydrochloric acid to provide a solution containing approximately 25µg of desipramine hydrochloride per mL.Concomitantly determine the absorbances of this solution and a Standard solution of USP Desipramine Hydrochloride RSin the same medium having a known concentration of about 25µg per mLin 1-cm cells at the wavelength of maximum absorbance at about 251nm,with a suitable spectrophotometer,using 0.1Nhydrochloric acid as the blank.Calculate the quantity,in mg,of C18H22N2·HCl in the tablet taken by the formula: in which Tis the labeled quantity,in mg,of desipramine hydrochloride in the Tablet,Cis the concentration,in µg per mL,of USP Desipramine Hydrochloride RSin the Standard solution,Dis the concentration,in µg per mL,of desipramine hydrochloride in the test solution,based upon the labeled quantity per Tablet and the extent of dilution,and AUand ASare the absorbances of the solution from the Tablet and the Standard solution,respectively.

Standard preparation— Dissolve a suitable quantity of USP Desipramine Hydrochloride RS,accurately weighed,in 0.1Nhydrochloric acid,and dilute quantitatively and stepwise with the same solvent to obtain a solution having a known concentration of about 25µg per mL.

Assay preparation— Finely powder a number of Tablets,equivalent to about 0.5g of desipramine hydrochloride,and transfer the powder to a 500-mLvolumetric flask with the aid of 100mLof 0.1Nhydrochloric acid.Add 150mLof the 0.1Nacid to the mixture,insert the stopper,and shake by mechanical means for 30minutes.Dilute with 0.1Nhydrochloric acid to volume,mix,and filter,discarding the first 10mLof the filtrate.Transfer 5.0mLof the subsequent filtrate to a 200-mLvolumetric flask,dilute with 0.1Nhydrochloric acid to volume,and mix.

Procedure— Transfer 15.0mLeach of the Standard preparationand the Assay preparation,respectively,to separate glass-stoppered,50-mLcentrifuge tubes,and to each tube add 2mLof 2.5Nsodium hydroxide and 15.0mLof cyclohexane suitable for use in UVspectrophotometry.Insert the stoppers,shake the tubes by mechanical means for 30minutes,and centrifuge at about 1500rpm until the clear phases separate (5to 10minutes).Concomitantly determine the absorbances of the cyclohexane extracts in 1-cm cells at the wavelength of maximum absorbance at about 255nm,with a suitable spectrophotometer,using cyclohexane suitable for use in UVspectrophotometry as the blank.Calculate the quantity,in mg,of C18H22N2·HCl in the portion of Tablets taken by the formula: in which Cis the concentration,in µg per mL,of USP Desipramine Hydrochloride RSin the Standard preparation,and AUand ASare the absorbances of the solutions from the Assay preparationand the Standard preparation,respectively.