Chromatographic purity
Dissolve 30 mg in 3.0 mL of chloroform (
Test solution). Dissolve a suitable quantity of
USP Ketoconazole RS in chloroform to obtain a
Standard solution having a known concentration of 10 mg per mL. Dilute a portion of this solution quantitatively with chloroform to obtain a
Diluted standard solution having a concentration of 1.0 mg per mL. Apply separate 10-µL portions of the
Test solution and the
Standard solution and a 2-µL portion of the
Diluted standard solution to the starting line of a suitable thin-layer chromatographic plate (see
Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Allow the spots to dry, and develop the chromatogram in a suitable unsaturated chamber with a solvent system consisting of a mixture of
n-hexane, ethyl acetate, methanol, water, and glacial acetic acid (42:40:15:2:1) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the chamber, and air-dry. Expose the plate to iodine vapors in a closed chamber, and locate the spots: the principal spot obtained from the
Test solution has about the same size and
RF value as that obtained from the
Standard solution, and the sum of the intensities of any secondary spots obtained from the
Test solution does not exceed the intensity of the principal spot obtained from the
Diluted standard solution.