A: The retention time of the Ethchlorvynol peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay.

B: Dissolve an amount of the contents of the Capsules,equivalent to about 1g of ethchlorvynol,in 20mLof methanol:the solution responds to Identificationtests Band Cunder Ethchlorvynol.

Medium: water;500mL.

Apparatus 2: 50rpm.

Time: 15minutes.

Procedure— Place 1Capsule in each vessel,and allow the Capsule to sink to the bottom of the vessel before starting rotation of the blade.Observe the Capsules,and record the time taken for each capsule shell to rupture.

Tolerances— The requirements are met if all of the Capsules tested rupture in not more than 15minutes.If 1or 2of the Capsules rupture in more than 15but not more than 30minutes,repeat the test on 12additional Capsules.Not more than 2of the total of 18Capsules tested rupture in more than 15but not more than 30minutes.

Methanol solution— Add 600mLof methanol to 1400mLof water in a suitable container,and mix.Allow the solution to equilibrate to room temperature.

Internal standard solution— Dissolve a quantity of chlorobutanol in Methanol solutionto obtain a solution having a known concentration of about 6mg per mL.

Standard preparation— Dissolve an accurately weighed quantity of USP Ethchlorvynol RSin Methanol solutionto obtain a solution having a known concentration of about 4mg per mL.Transfer 5.0mLof this solution to a suitable flask,add 5.0mLof Internal standard solution,and mix to obtain a Standard preparationhaving a known concentration of about 2mg of USP Ethchlorvynol RSper mL.

Assay preparation— Transfer not less than 20Capsules,accurately counted,to a 500-mLvolumetric flask.Add 250mLof Methanol solution,heat at 70to 80for not more than 3hours,and stir until the Capsules burst.Cool the solution to room temperature,add Methanol solutionto volume,and mix.Quantitatively dilute a portion of this solution if necessary with Methanol solutionto obtain a solution containing about 4mg of E-ethchlorvynol per mL,and mix.Transfer 5.0mLof this solution to a suitable flask,add 5.0mLof Internal standard solution,and mix to obtain an Assay preparationcontaining about 2mg of E-ethchlorvynol per mL.

Chromatographic system (see Chromatography á621ñ)—The gas chromatograph is equipped with a flame-ionization detector and a 1.8-m ×4-mm glass column (pretreated with 10%dimethyldichlorosilane in toluene)packed with 10%phase G16on 60-to 80-mesh support S1AB.The column is maintained at about 160,and the injector and the detector are maintained at about 200.The carrier gas is dry helium,flowing at a rate of about 30mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed under Procedure:the resolution,R,between the ethchlorvynol and chlorobutanol peaks is not less than 4.0,and the relative standard deviation for replicate injections is not more than 1.5%.

Procedure— Separately inject equal volumes (about 2µL)of the Standard preparationand the Assay preparationinto the gas chromatograph,record the chromatographs,and measure the responses for the major peaks.The relative retention times are about 0.55for chlorobutanol and 1.0for E-ethchlorvynol.Calculate the quantity,in mg,of E-ethchlorvynol (C7H9ClO)in each Capsule taken by the formula: in which Cis the concentration,in mg per mL,of USP Ethchlorvynol RSin the Standard preparation,Lis the labeled quantity,in mg,of ethchlorvynol in each Capsule,Dis the concentration,in mg per mL,of ethchlorvynol in each mLof the Assay preparationbased on the number of Capsules taken,the labeled quantity,in mg,of ethchlorvynol in each Capsule,and the extent of dilution,and RUand RSare the peak response ratios obtained from the Assay preparationand the Standard preparation,respectively.