NOTE—Throughout the following procedures, protect test or assay specimens, the Reference Standard, and solutions containing them, by conducting the procedures without delay, under subdued light, or using low-actinic glassware.

Medium: 0.1 N hydrochloric acid; 500 mL.

Apparatus 2: 75 rpm.

Time: 60 minutes.

Procedure— Determine the amount of prochlorperazine (C20H24ClN3S) dissolved from UV absorbances at the wavelength of maximum absorbance at about 254 nm of filtered portions of the solution under test, suitably diluted with Dissolution Medium, if necessary, in comparison with a Standard solution having a known concentration of USP Prochlorperazine Maleate RS in the same Medium.

Tolerances— Not less than 75% (Q) of the labeled amount of C20H24ClN3S is dissolved in 60 minutes.

(Official January 1, 2007)

Ion-pairing solution— Transfer 4.33 g of sodium 1-octanesulfonate, accurately weighed, to a 1-liter volumetric flask. Dissolve in 500 mL of water, add 4.0 mL of glacial acetic acid, dilute with water to volume, and mix.

Mobile phase— Prepare a suitable filtered and degassed mixture of Ion-pairing solution, acetonitrile, and methanol (45:40:15).

Standard preparation— Dissolve an accurately weighed quantity of USP Prochlorperazine Maleate RS in Mobile phase to obtain a solution having a known concentration of about 0.2 mg per mL.

Assay preparation— Weigh and finely powder not less than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 20 mg of prochlorperazine maleate, to a 100-mL volumetric flask. Add 60 mL of Mobile phase, sonicate for 3 minutes, and shake by mechanical means for 30 minutes. Dilute with Mobile phase to volume, mix, and filter, discarding the first 10 mL of filtrate.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm × 30-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 tailing factor for the analyte peak is not more than 2.0; 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 prochlorperazine (C20H24ClN3S) in the portion of Tablets taken by the formula: in which 373.94 and 606.09 are the molecular weights of prochlorperazine and prochlorperazine maleate, respectively; C is the concentration, in mg per mL, of USP Prochlorperazine Maleate RS in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.