A: Infrared Absorption á197Kñ.

B: Asolution of it responds to the ferrous sulfate-sulfuric acid test for Nitrate á191ñ.

Test solution— Prepare a solution of it,in a mixture of dichloromethane and methanol (2:1),having an accurately known concentration of 20mg per mL.

Standard solutions— Dissolve USP Sulconazole Nitrate RSin a mixture of dichloromethane and methanol (2:1),and dilute quantitatively with the same mixture to obtain separate solutions having accurately known concentrations of 0.02,0.1,0.2,and 0.4mg per mL,respectively.

Eluant: a mixture of methylene chloride,cyclohexane,and diethylamine (50:45:5).

Visualization: 22.

Mobile phase— Dissolve 1.9g of sodium 1-pentanesulfonate in 300mLof water,add 700mLof methanol,and mix.Adjust with 2Nsulfuric acid to an apparent pHof 3.8±0.1,filter,and degas.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

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

Assay preparation— Transfer about 20mg of Sulconazole Nitrate,accurately weighed,to a 100-mLvolumetric flask,dissolve in Mobile phase,dilute with Mobile phaseto volume,and mix.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 230-nm detector and a 4.6-mm ×25-cm column that contains packing L1and is maintained at 40±1.0.The flow rate is about 2mLper 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 sulconazole nitrate peak is not more than 2.3,and the relative standard deviation for replicate injections is not more than 1.5%.

Procedure— Separately inject equal volumes (about 10µL)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 C18H15Cl3N2S·HNO3in the portion of Sulconazole Nitrate taken by the formula: in which Cis the concentration,in mg per mL,of USP Sulconazole Nitrate RSin the Standard preparation,and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.