(Official January 1, 2007)

Mobile phase— Mix approximately equal volumes of acetonitrile and water, adjusting the ratio of solvents as necessary to achieve acceptable chromatography.

Internal standard solution— Transfer 15 mg of Progesterone to a 50-mL volumetric flask. Dissolve in Mobile phase, dilute with Mobile phase to volume, and mix.

Standard preparation— Transfer about 20 mg of USP Halcinonide RS, accurately weighed, to a 100-mL volumetric flask, dissolve in Mobile phase, dilute with Mobile phase to volume, and mix. Transfer 5.0 mL of this solution to a 50-mL volumetric flask, add 2.0 mL of Internal standard solution, dilute with Mobile phase to volume, and mix.

Assay preparation— Transfer an accurately measured quantity of Topical Solution, equivalent to about 1 mg of halcinonide, to a 50-mL volumetric flask, add 2.0 mL of Internal standard solution, dilute with Mobile phase to volume, and mix.

Chromatographic system and Procedure— Proceed as directed in the Assay under Halcinonide Cream. Calculate the quantity, in mg, of C24H32ClFO5 in the portion of Topical Solution taken by the formula: in which the terms are as defined therein.