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

A: To 2mLof Oral Solution add 3mLof water and 3or 4drops of ferric chloride TS:a stable red color is produced.

B: To 1mLof Oral Solution add 10mLof bromine TS,previously warmed to room temperature:essentially no color change occurs (distinction from chlorpromazine hydrochloride,which immediately produces a green color).

FOR ORAL SOLUTION PACKAGED IN SINGLE-UNIT CONTAINERS: meets the requirements.

FOR ORAL SOLUTION PACKAGED IN MULTIPLE-UNIT CONTAINERS: meets the requirements.

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

Mobile phase— Prepare a filtered and degassed mixture of Ion-pairing solution,acetonitrile,and methanol (50:40:10).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Diluting solution— Prepare a mixture containing 1000mLof distilled water,8.6mLof concentrated hydrochloric acid,and 1000mLof methanol.

Standard stock solution— Dissolve an accurately weighed quantity of USP Prochlorperazine Maleate RSin Diluting solution;and dilute quantitatively,and stepwise if necessary,with Diluting solutionto obtain a solution having a known concentration of about 1.0mg per mL.

Internal standard solution— Prepare a solution of trifluoperazine hydrochloride in Diluting solutioncontaining about 0.9mg per mL.

Standard preparation— Pipet 10.0mLof the Standard stock solutionand 10.0mLof the Internal standard solutioninto a 100-mLvolumetric flask.Dilute with Diluting solutionto volume,and mix.

Assay preparation— Transfer a quantity of Oral Solution,equivalent to about 10.0mg of prochlorperazine,to a 100-mLvolumetric flask;add 10.0mLof Internal standard solution;dilute with Diluting solutionto volume;and mix.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm ×15-cm column that contains 10-µm packing L1.The flow rate is about 1.5mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the relative retention times are about 1.3for trifluoperazine and 1.0for prochlorperazine;the resolution,R,between prochlorperazine and the internal standard is not less than 2.0;the tailing factor 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 10µL)of the Standard preparationand the Assay preparationinto 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 Oral Solution taken by the formula: in which 373.94and 606.09are the molecular weights of prochlorperazine and prochlorperazine maleate,respectively;Cis the concentration,in mg per mL,of USP Prochlorperazine Maleate RSin the Standard preparation;and RUand RSare the ratios of the prochlorperazine peak to the internal standard peak obtained from the Assay preparationand the Standard preparation,respectively.