A: Transfer a quantity of finely powdered Tablets,equivalent to about 10mg of amitriptyline hydrochloride,to a 100-mLvolumetric flask,add 50mLof methanol,shake well,then add methanol to volume.Filter a portion of this solution,and dilute 10mLof the filtrate with methanol to 100mL:the UVabsorption spectrum of this solution exhibits a maximum at the same wavelength as that of a similar solution of USP Amitriptyline Hydrochloride RS,concomitantly measured.

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

Medium: 0.1Nhydrochloric acid;900mL.

Apparatus 1: 100rpm.

Time: 45minutes.

Procedure— Determine the amount of C20H23N·HCl dissolved from UVabsorbances at the wavelength of maximum absorbance at about 239nm on 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 Amitriptyline Hydrochloride RSin the same Medium.

Tolerances— Not less than 75%(Q)of the labeled amount of C20H23N·HCl is dissolved in 45minutes.

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

Standard preparation— Dissolve an accurately weighed quantity of USP Amitriptyline Hydrochloride RSin Mobile phase,and quantitatively dilute with Mobile phaseto obtain a solution having a known concentration of about 0.2mg per mL.

Assay preparation— Transfer 20Tablets to a 500-mLvolumetric flask,add 250mLof Mobile phase,and shake the mixture for 1hour or until the tablets have disintegrated.Add Mobile phaseto volume,mix,and filter.Quantitatively dilute an accurately measured volume (VFmL)of the clear filtrate with Mobile phaseto obtain a solution (VAmL)containing about 0.2mg of amitriptyline hydrochloride per mL.

Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of amitriptyline hydrochloride (C20H23N·HCl)in each Tablet taken by the formula: in which Cis the concentration,in mg per mL,of USP Amitriptyline Hydrochloride RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.