(Official January 1, 2007)

Chromatographic solvent— Equilibrate, by shaking in a separator, 95 mL of alcohol, 5 mL of water, and 50 mL of chromatographic n-heptane. Allow the layers to separate.

Isoniazid reagent— Dissolve 375 mg of isoniazid and 0.47 mL of hydrochloric acid in 500 mL of methanol.

Standard preparation— Dissolve a suitable quantity of USP Testosterone Enanthate RS, accurately weighed, in methanol, and dilute quantitatively and stepwise with methanol to obtain a solution having a known concentration of about 40 µg per mL.

Assay preparation— Transfer to a 10-mL volumetric flask an accurately measured volume of Injection, equivalent to about 100 mg of testosterone enanthate, add chromatographic n-heptane to volume, and mix. Pipet 5 mL of this solution into a 100-mL volumetric flask, add chromatographic n-heptane to volume, and mix.

Procedure— Mix in a beaker 3 g of silanized chromatographic siliceous earth and 3 mL of the upper layer of the Chromatographic solvent. Pack the mixture into a 250- × 25-mm chromatographic tube that contains a small pledget of glass wool above the stem constriction. Mix in a beaker 3 g of silanized chromatographic siliceous earth and 2.0 mL of Assay preparation, transfer the mixture to the tube, and pack. Dry-wash the beaker with 1 g of silanized chromatographic siliceous earth, and transfer to the tube. Place a small pad of glass wool above the column packing. Pass 35 mL of the lower layer of the Chromatographic solvent through the column, and collect the eluate in a 50-mL volumetric flask. Add alcohol to volume, and mix. Pipet 10 mL of the resulting solution into a glass-stoppered, 50-mL conical flask, and evaporate on a water bath to dryness. Pipet 5 mL of methanol into the flask, and swirl to dissolve the residue. Pipet 5 mL of Standard preparation into a similar flask. To each flask add 10.0 mL of Isoniazid reagent, mix, and allow to stand for about 45 minutes. Concomitantly determine the absorbances of both solutions at the wavelength of maximum absorbance at about 380 nm, with a suitable spectrophotometer, using as a blank 5 mL of methanol that has been treated similarly with Isoniazid reagent. Calculate the quantity, in mg, of C26H40O3 in each mL of the Injection taken by the formula: in which C is the concentration, in µg per mL, of USP Testosterone Enanthate RS in the Standard preparation; V is the volume, in mL, of Injection taken; and AU and AS are the absorbances of the solutions from the Assay preparation and the Standard preparation, respectively.