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: 0.01Nhydrochloric acid;1000mL.

Apparatus 1: 120rpm.

Time: 30minutes.

Procedure— Determine the amount of C22H29N3S2·2C4H4O4dissolved by employing UVabsorption at the wavelength of maximum absorbance at about 263nm on 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 Thiethylperazine Maleate RSin the same Medium.

Tolerances— Not less than 75%(Q)of the labeled amount of C22H29N3S2·2C4H4O4is dissolved in 30minutes.

Mobile phase— Proceed as directed under the Assayfor Thiethylperazine Maleate Suppositories.

Diluent— Prepare a mixture of acetonitrile and water (9:1).

Standard preparation— Dissolve an accurately weighed quantity of USP Thiethylperazine Maleate RSin Diluentby sonicating for about 5minutes,and dilute quantitatively,and stepwise if necessary,with Diluentto obtain a solution having a known concentration of about 0.2mg per mL.

Assay preparation— Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 50mg of thiethylperazine maleate,to a 250-mLvolumetric flask.Add 150mLof Diluent,and shake to disperse the powder.Sonicate the mixture for 10minutes,then shake by mechanical means for 1hour.Dilute with Diluentto volume,and mix.Filter through a 0.45-µm filter,discarding the first portion of the filtrate.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 265-nm detector and a 4.6-mm ×25-cm column that contains 5-µm,base-deactivated packing L1.The flow rate is about 2mLper minute,and the column temperature is maintained at 45.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the resolution,R,between the thiethylperazine peak and adjacent peaks is not less than 1.5,the column efficiency is not less than 1000theoretical plates,the tailing factor for thiethylperazine is not more than 2.5,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 C22H29N3S2·2C4H4O4in the portion of Tablets taken by the formula: in which Cis the concentration,in mg per mL,of USP Thiethylperazine Maleate RSin the Standard preparation,and rUand rSare the peak responses obtained from the Assay preparationand the Standard preparation,respectively.