Free heptanoic acid
Dissolve 500 mg in 10 mL of alcohol that previously has been neutralized to a faint blue color following the addition of 2 or 3 drops of bromothymol blue TS
, and promptly titrate with 0.01 N sodium hydroxide VS: not more than 0.6 mL of 0.01 N sodium hydroxide is required (0.16% of heptanoic acid).
Ordinary impurities 466
a mixture of cyclohexane and ethyl acetate (2:1).
No individual impurity exceeds 1.0%, and the total of observed impurities does not exceed 2.0%.
Dissolve about 40 mg of Testosterone Enanthate, accurately weighed, in chloroform to make 100 mL, and mix. Pipet 10 mL of this solution into a 100-mL volumetric flask, add chloroform to volume, and mix. Dissolve a suitable quantity of USP Testosterone Enanthate RS
, accurately weighed, in chloroform, and dilute quantitatively and stepwise with chloroform to obtain a Standard solution having a known concentration of about 40 µg per mL. Pipet 5 mL each of the solution of Testosterone Enanthate and the Standard solution into separate, glass-stoppered, 50-mL conical flasks, and place 5.0 mL of chloroform in a similar flask to provide a blank. Treat each flask as follows. Add 10.0 mL of a solution of 375 mg of isoniazid and 0.47 mL of hydrochloric acid in 500 mL of methanol, mix, and allow to stand for 45 minutes. Concomitantly determine the absorbances of the solutions at the wavelength of maximum absorbance at about 380 nm, with a suitable spectrophotometer, using the blank to set the instrument. Calculate the quantity, in mg, of C26
in the Testosterone Enanthate taken by the formula:
C(AU / AS),
in which C
is the concentration, in µg per mL, of USP Testosterone Enanthate RS
in the Standard solution; and AU
are the absorbances of the solution of Testosterone Enanthate and the Standard solution, respectively.