A: The Tablets meet the requirements under Identification—Organic Nitrogenous Bases á181ñ.

B: The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that of the Standard preparationas obtained in the Assay.

Medium: water;900mL.

Apparatus 2: 50rpm.

Time: 45minutes.

Procedure— Determine the amount of C13H19NO·HCl dissolved from UVabsorbances at the wavelength of maximum absorbance at about 253nm of filtered portions of the solution under test,suitably diluted with 0.1Nhydrochloric acid,in comparison with a Standard solution having a known concentration of USP Diethylpropion Hydrochloride RSin the same medium.

Tolerances— Not less than 75%(Q)of the labeled amount of C13H19NO·HCl is dissolved in 45minutes.

Phosphate buffer,Mobile phase,and Chromatographic system— Prepare as directed in the Assayunder Diethylpropion Hydrochloride.

Standard preparation— Dissolve an accurately weighed quantity of USP Diethylpropion Hydrochloride RSin 0.1Nhydrochloric acid,and dilute quantitatively,and stepwise if necessary,with 0.1Nhydrochloric acid to obtain a stock solution having a known concentration of about 160µg per mL.Transfer 5.0mLof this stock solution to a 100-mLvolumetric flask,dilute with Mobile phaseto volume,and mix to obtain a solution having a known concentration of about 8µg per mL.

Assay preparation— Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 40mg of diethylpropion hydrochloride,to a 250-mLvolumetric flask.Add 200mLof 0.1Nhydrochloric acid,and stir with the aid of a stir bar for 45minutes.Remove the stir bar,dilute with 0.1Nhydrochloric acid to volume,mix,and filter,discarding the first 25mLof the filtrate.Transfer 5.0mLof the filtrate to a 100-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.If necessary,filter the solution through a 0.7-µm porosity membrane filter.

System suitability preparation— Dissolve benzoic acid in 0.1Nhydrochloric acid to obtain a solution having a concentration of about 1mg per mL.Transfer 10.0mLof this solution to a 100-mLvolumetric flask,add 5.0mLof the stock solution prepared as directed for the Standard preparation,dilute with Mobile phaseto volume,and mix.

Procedure— Proceed as directed for Procedurein the Assayunder Diethylpropion Hydrochloride.Calculate the quantity,in mg,of C13H19NO·HCl in the portion of Tablets taken by the formula: in which Cis the concentration,in µg per mL,of USP Diethylpropion Hydrochloride RSin the Standard preparation,and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.