A: Infrared Absorption á197Kñ.

B: [NOTE—Conduct this test promptly,with a minimum exposure to light.]Dissolve 25.0mg of it,previously dried,in 0.25mLof chloroform;mix with about 30mLof methanol previously warmed to 50;transfer the mixture with the aid of warm methanol to a 250-mLvolumetric flask;cool the solution to room temperature;dilute with methanol to volume;and mix.Pipet 10mLof this solution into a 50-mLvolumetric flask,add 36mLof chloroform,dilute with methanol to volume,and mix:the UVabsorption spectrum of a 1in 50,000solution so obtained exhibits the same maxima in the range of 255nm to 350nm as that of a similar solution of USP Reserpine RS,concomitantly measured;and the respective absorptivities,determined with reference to a mixture of 36volumes of chloroform and 14volumes of methanol as the blank,at the wavelength of maximum absorbance at about 268nm,do not differ by more than 3.0%.

Mobile phase— Prepare a filtered and degassed 1:1mixture of acetonitrile and ammonium chloride solution (1in 100).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).The pHis about 5.6.

Standard preparation— Dissolve an accurately weighed quantity of USP Reserpine RSin Mobile phase,and dilute quantitatively,and stepwise if necessary,with Mobile phaseto obtain a solution having a known concentration of about 10µg per mL.

Assay preparation— Transfer about 10mg of Reserpine,accurately weighed,to a 100-mLvolumetric flask.Dilute with Mobile phaseto volume,and mix.Dilute 1.0mLof this solution with 9.0mLof Mobile phase,and mix.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 268-nm detector and a 4.6-mm ×25-cm column that contains packing L1.The flow rate is about 1.5mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency determined from the analyte peak is not less than 1500theoretical plates;the tailing factor for the analyte peak is not more than 1.5;and the relative standard deviation for replicate injections is not more than 2.0%.

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 C33H40N2O9in the portion of Reserpine taken by the formula: in which Cis the concentration,in µg per mL,of USP Reserpine RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.