Melting range 741:
, with decomposition. Occasionally it may show preliminary melting at about 135
, followed by resolidification.
Prepare a filtered and degassed mixture of methanol and water (60:40).
Dissolve an accurately weighed quantity of USP Spironolactone RS
in a mixture of acetonitrile and water (50:50), and quantitatively dilute with the same mixture to obtain a solution having a known concentration of about 0.5 mg of USP Spironolactone RS
Transfer about 50 mg of Spironolactone, accurately weighed, to a 100-mL volumetric flask, add a mixture of acetonitrile and water (50:50) to volume, and mix.
Chromatographic system (see Chromatography 621)
The liquid chromatograph is equipped with a 230-nm detector and a 4.6-mm × 15-cm column that contains packing L1. The flow rate is about 1 mL per minute. Chromatograph the Standard preparation,
and record the peak responses as directed for Procedure:
the tailing factor is not more than 2.0; and the relative standard deviation for replicate injections is not more than 1.5%.
Separately inject equal volumes (about 20 µL) of the Standard preparation
and the Assay preparation
into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C24
S in the portion of Spironolactone taken by the formula:
100C(rU / rS),
in which C
is the concentration, in mg per mL, of USP Spironolactone RS
in the Standard preparation;
are the spironolactone peak responses obtained from the Assay preparation
and the Standard preparation,