A: The Tablets meet the requirements under Identification—Organic Nitrogenous Bases 181.

B: The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that of the Standard preparation as obtained in the Assay.

Medium: water; 900 mL.

Apparatus 2: 50 rpm.

Time: 45 minutes.

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

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

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

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

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

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

Procedure— Proceed as directed for Procedure in the Assay under Diethylpropion Hydrochloride. Calculate the quantity, in mg, of C13H19NO·HCl in the portion of Tablets taken by the formula: in which C is the concentration, in µg per mL, of USP Diethylpropion Hydrochloride RS in the Standard preparation, and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.