Procedure
Separately apply 10-µL portions of the
Standard solutions A and
B and the
Test solution to a suitable thin-layer chromatographic plate (see
Chromatography 621), coated with a 0.25-mm layer of chromatographic silica gel. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of a mixture of toluene, dehydrated alcohol, and ammonium hydroxide (170:28:2) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the chamber, allow to air-dry, and spray with Potassium Bismuth Iodide TS: the
RF value of the principal spot obtained from the
Test solution corresponds to that obtained from
Standard solution B. Estimate the levels of any additional spots observed in the chromatogram of the
Test preparation by comparison with the principal spots in the chromatograms of
Standard solutions A and
B: the sum of the intensities of any additional spots observed is not greater than that obtained from
Standard solution B (equivalent to 1%).