A: Infrared Absorption á197Kñ.

B: Ultraviolet Absorption á197Uñ—

Mobile phase— Prepare a filtered and degassed mixture of 0.2Mammonium acetate,methanol,and acetonitrile (38:32:30).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Resolution solution— Dissolve accurately weighed quantities of USP Miconazole Nitrate RSand USP Econazole Nitrate RSin Mobile phaseto obtain a solution having known concentrations of about 25µg of each per mL.

Test solution— Transfer 100mg of Miconazole Nitrate to a 10-mLvolumetric flask,add Mobile phaseto volume,and mix.

Diluted test solution— Dilute an accurately measured volume of the Test solutionquantitatively,and stepwise if necessary,with Mobile phaseto obtain a solution containing 25µg of miconazole nitrate per mL.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 235-nm detector and a 4.6-mm ×10-cm column that contains 3-µm packing L1.The flow rate is about 2mLper minute.Chromatograph theResolution solution,and record the peak responses as directed forProcedure:the relative retention times are about 0.5for econazole and 1.0for miconazole;the resolution,R,between econazole and miconazole is not less than 10;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10µL)of the Test solutionand Diluted test solutioninto the chromatograph,record the chromatograms for a time that is 1.2times the retention time of the main peak,and measure the responses of all peaks,excluding the peak representing nitrate ion and any peak producing a response less than 0.2times the response of the main peak.The response of any individual peak,other than the main peak in the chromatogram of the Test solution,is not greater than that of the main peak in the chromatogram of the Diluted test solution(0.25%),and the sum of the responses of all peaks,other than the main peak in the chromatogram of the Test solution,is not greater than twice the response of the main peak in the chromatogram of the Diluted test solution(0.5%).