A: Infrared Absorption á197Kñ.

B: Ultraviolet Absorption á197Uñ—

Solution: 800µg per mL.

Medium: 0.1Nhydrochloric acid in methanol (1in 10).

C: Shake 10mg with 5mLof water,and cool the resulting suspension in ice.Keeping the suspension cool,add 0.4mLof potassium chloride solution (1in 10),0.1mLof diphenylamine TS,and dropwise,with shaking,5mLof sulfuric acid:an intense blue color develops.

Standard preparation— Dissolve an accurately weighed quantity of USP Econazole Nitrate RSin methanol to obtain a solution containing 75µg per mL.

Test preparation— Dissolve an accurately weighed quantity of Econazole Nitrate in methanol to obtain a solution containing 20mg per mL.

Procedure— Apply separately 20µLof the Test preparationand 20µLof the Standard preparationto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel.Allow the spots to dry,place the plate in a chromatographic chamber,and develop the chromatograms in a solvent system consisting of a mixture of 1,4-dioxane,toluene,and 13.5Mammonium hydroxide (60:40:1)until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the developing chamber,mark the solvent front,and dry the plate in a current of air.Expose the plate to iodine vapors for 1hour,and air-dry until the iodine has dissipated.Compare the intensities of any secondary spots observed in the chromatogram of the Test preparationwith that of the principal spot in the chromatogram of the Standard preparation:no individual secondary spots in the chromatogram of the Test preparationare larger or more intense than the principal spot produced by the Standard preparation,corresponding to not more than 0.375%,and the total of all such secondary spots observed is not more than 2.0%.