A: Infrared Absorption á197Kñ.

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.

Solvent— Use dimethyl sulfoxide.

Buffer solution A— Dissolve 68g of monobasic potassium phosphate in 1000mLof water.

Buffer solution B— Dilute 100mLof Buffer solution Awith water to 1000mL,and adjust with 45%potassium hydroxide solution to a pHof 7.0.

Mobile phase— Prepare a filtered and degassed mixture of methanol and Buffer solution B(70:30).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Disulfiram RSin alcohol with sonication and swirling if necessary to obtain a solution having a known concentration of about 1mg per mL.[NOTE—Discard this solution after 5days.]Quantitatively dilute this solution with Mobile phaseto obtain the Standard preparationhaving a known concentration of about 0.02mg of USP Disulfiram RSper mL.[NOTE—Prepare the Standard preparation fresh daily.]

Assay preparation— Transfer about 50mg of Disulfiram,accurately weighed,to a 50-mLvolumetric flask,add about 40mLof alcohol,sonicate for 5minutes to completely dissolve,cool,dilute with alcohol to volume,and mix.[NOTE—Discard this solution after 5days.]Quantitatively dilute this solution with Mobile phaseto obtain the Assay preparationhaving a concentration of about 0.02mg per mL.[NOTE—Prepare the Assay preparation fresh daily.]

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 250-nm detector and a 4-mm ×15-cm column that contains 5-µm packing L1.The flow rate is about 1mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed under Procedure:the column efficiency determined from the analyte peak is not less than 1800plates;the tailing factor,T,for the analyte peak is not more than 2;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 C10H20N2S4in the portion of Disulfiram taken by the formula: in which Cis the concentration,in µg per mL,of USP Disulfiram RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.