Standard solutions— Dissolve an accurately weighed quantity of USP Amoxapine RSin chloroform,and mix to obtain Standard preparation Ahaving a known concentration of 0.50mg per mL.Quantitatively dilute a portion of Standard solution Awith chloroform to obtain Standard solution Bhaving a known concentration of 0.25mg per mL.

Test solution— Dissolve an accurately weighed quantity of Amoxapine in chloroform to obtain a solution containing 50mg per mL.

Procedure— Separately apply 5µLof the Test solutionand each of the two Standard solutionsto a suitable thin-layer chromatographic plate (see Chromatography á621ñ),coated with a 0.2-mm layer of chromatographic silica gel mixture.Allow the spots to dry,and develop the chromatogram in a solvent system consisting of a mixture of chloroform,methanol,and ammonium hydroxide (18:2:0.1)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,air-dry,examine the plate under short-wavelength UVlight,and compare the intensities of any secondary spots observed in the chromatogram of the Test solutionwith those of the principal spots in the chromatograms of the Standard solutions:no secondary spot from the chromatogram of the Test solutionis larger or more intense than the principal spot obtained from Standard solution B(0.5%),and the sum of the intensities of the secondary spots obtained from the Test solutioncorresponds to not more than 1.0%.