Test solution: 50 mg, previously dried, per mL, in chloroform.

Phosphomolybdic acid reagent— Add 10 g of phosphomolybdic acid to 100 mL of alcohol, and stir the mixture for not less than 30 minutes. Filter before use.

Test preparation— Prepare a solution of Norgestrel in chloroform to contain 10.0 mg per mL.

Standard solution and Standard dilutions— Prepare a solution of USP Norgestrel RS in chloroform to contain 10 mg per mL (Standard solution). Prepare a series of dilutions of Standard solution in chloroform to contain 0.20, 0.10, 0.05, 0.02, and 0.01 mg per mL (Standard dilutions).

Procedure— Apply 10-µL volumes of Standard solution, the Test preparation, and each of the five Standard dilutions at equidistant points along a line 2.5 cm from one edge of a 20- × 20-cm thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture and previously activated by heating at 100 for 15 minutes. Place the plate in a suitable developing chamber that contains and has been equilibrated with a mixture of 96 volumes of chloroform and 4 volumes of alcohol, seal the chamber, and allow the chromatogram to develop until the solvent front has moved 15 cm above the line of application. Remove the plate, allow the solvent to evaporate, then spray uniformly with Phosphomolybdic acid reagent, and heat it at 105 for 10 to 15 minutes. The lane of the Test preparation exhibits its principal spot at the same RF as the principal spot of Standard solution. If spots other than the principal spot are observed in the lane of the Test preparation, estimate the concentration of each by comparison with the Standard dilutions. The spots from the 0.20-, 0.10-, 0.05-, 0.02-, and 0.01-mg per mL dilutions are equivalent to 2.0, 1.0, 0.5, 0.2, and 0.1% of impurities, respectively. The requirements of the test are met if the sum of the impurities in the Test preparation does not exceed 2.0%.

(Official January 1, 2007)

10C(AU / AS),