Identification—
The chromatogram of the
Assay preparation obtained as directed in the
Assay exhibits a major peak for azaperone, the retention time of which corresponds to that exhibited in the chromatogram of the
Standard preparation, obtained as directed in the
Assay.
Assay—
Mobile phase—
Prepare a filtered and degassed mixture containing 6 volumes of acetonitrile and 4 volumes of 0.01
M dibasic potassium phosphate, and adjust by the addition of dilute phosphoric acid (1 in 10) to a pH of 7.8 ± 0.1. Make adjustments if necessary (see
System Suitability under
Chromatography 
621
).
Internal standard solution—
Prepare a solution of benzophenone in methanol containing about 0.5 mg per mL.
Standard preparation—
Dissolve an accurately weighed quantity of
USP Azaperone RS in methanol, and dilute quantitatively with methanol to obtain a solution having a known concentration of about 0.5 mg per mL. Combine 2.5 mL of this solution with 2.5 mL of
Internal standard solution, dilute quantitatively with methanol to 10.0 mL, and mix.
Assay preparation—
Dilute an accurately measured volume of Injection quantitatively with methanol to obtain a solution containing about 0.5 mg of azaperone per mL. Combine 2.5 mL of this solution with 2.5 mL of
Internal standard solution, dilute quantitatively with methanol to 10.0 mL, and mix.
Chromatographic system
(see
Chromatography 621)—The liquid chromatograph is equipped with 243-nm detector and a 4.6-mm × 25-cm column that contains packing L1. The flow rate is about 2 mL per minute. Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the resolution,
R, between the azaperone and internal standard peaks is not less than 2.7; and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 10 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 azaperone (C
19H
22FN
3O) in each mL of the Injection taken by the formula:
(C)(L / D)(RU / RS),
in which
C is the concentration, in mg per mL, of
USP Azaperone RS in the
Standard preparation; L is the labeled quantity, in mg, of azaperone in each mL of the Injection;
D is the concentration, in mg per mL, of azaperone in the
Assay preparation, based on the volume of Injection taken and the extent of dilution; and
RU and
RS are the ratios of the azaperone peak to the benzophenone peak obtained from the
Assay preparation and the
Standard preparation, respectively.
