Medium: simulated gastric fluid TS(without the enzyme);900mL.

Apparatus 1: 100rpm.

Time: 60minutes.

Mobile phase— Prepare a pH4.0degassed and filtered mixture of methanol and 0.05Mmonobasic potassium phosphate buffer (60:40).Add 1Nsodium hydroxide or phosphoric acid,if necessary,to adjust the mixture to a pHof 4.0.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm ×25-cm column that contains packing L1.The flow rate is about 1mLper minute.Chromatograph the Standard solution,and record the peak responses as directed under Procedure:the relative standard deviation for replicate injections is not more than 3.0%,and the tailing factor is not more than 2.0.

Procedure— Separately inject equal volumes (about 50µL)of the Standard solution and filtered portions of the solution under test into the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity of C21H23ClFNO2dissolved in comparison with a Standard solution having a known concentration of USP Haloperidol RSin the same medium and similarly chromatographed.

Tolerances— Not less than 80%(Q)of the labeled amount of C21H23ClFNO2is dissolved in 60minutes.

Procedure for content uniformity— Transfer 1finely powdered Tablet to a suitable volumetric flask,and prepare a solution containing about 20µg per mLby adding warm methanol,shaking for 15minutes,diluting with methanol to volume,and filtering,discarding the first 20mLof the filtrate.Concomitantly determine the absorbances of this solution and of a solution of USP Haloperidol RSin the same medium,having a known concentration of about 20µg per mL,in 1-cm cells at the wavelength of maximum absorbance at about 245nm,with a suitable spectrophotometer,using methanol as the blank.Calculate the quantity,in mg,of C21H23ClFNO2in the Tablet by the formula: in which Tis the labeled quantity,in mg,of haloperidol in the Tablet,Dis the concentration,in µg per mL,of the solution from the Tablet,based upon the labeled quantity per Tablet and the extent of dilution,Cis the concentration,in µg per mL,of USP Haloperidol RSin the Standard solution,and AUand ASare the absorbances of the solution from the Tablet and the Standard solution,respectively.

Mobile phase— Prepare a pH4.0degassed and filtered mixture of methanol and 0.05Mmonobasic potassium phosphate buffer (60:40).Add 1Nsodium hydroxide or phosphoric acid,if necessary,to adjust the mixture to a pHof 4.0.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Haloperidol RSin Mobile phaseand dilute quantitatively,and stepwise if necessary,with Mobile phaseto obtain a solution having a known concentration of about 0.1mg per mL.

Assay preparation— Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 10mg of haloperidol,to a 100-mLvolumetric flask,add 60mLof Mobile phase,sonicate for 10minutes,and shake by mechanical means for about 1hour.Dilute with Mobile phaseto volume,mix,and filter,discarding the first 20mLof the filtrate.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm ×25-cm column that contains packing L1.The flow rate is about 1mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed under Procedure: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 15µL)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 C21H23ClFNO2in the portion of Tablets taken by the formula: in which Cis the concentration,in mg per mL,of USP Haloperidol RSin the Standard preparation;and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.