A: The retention time of the Ethchlorvynol peak in the chromatogram of the Assay preparation corresponds 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 1 g of ethchlorvynol, in 20 mL of methanol: the solution responds to Identification tests B and C under Ethchlorvynol.

Medium: water; 500 mL.

Apparatus 2: 50 rpm.

Time: 15 minutes.

Procedure— Place 1 Capsule 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 15 minutes. If 1 or 2 of the Capsules rupture in more than 15 but not more than 30 minutes, repeat the test on 12 additional Capsules. Not more than 2 of the total of 18 Capsules tested rupture in more than 15 but not more than 30 minutes.

Methanol solution— Add 600 mL of methanol to 1400 mL of 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 solution to obtain a solution having a known concentration of about 6 mg per mL.

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

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

Chromatographic system (see Chromatography 621)—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 G16 on 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 30 mL per 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 2 µL) of the Standard preparation and the Assay preparation into the gas chromatograph, record the chromatographs, and measure the responses for the major peaks. The relative retention times are about 0.55 for chlorobutanol and 1.0 for E-ethchlorvynol. Calculate the quantity, in mg, of E-ethchlorvynol (C7H9ClO) in each Capsule taken by the formula: in which C is the concentration, in mg per mL, of USP Ethchlorvynol RS in the Standard preparation, L is the labeled quantity, in mg, of ethchlorvynol in each Capsule, D is the concentration, in mg per mL, of ethchlorvynol in each mL of the Assay preparation based on the number of Capsules taken, the labeled quantity, in mg, of ethchlorvynol in each Capsule, and the extent of dilution, and RU and RS are the peak response ratios obtained from the Assay preparation and the Standard preparation, respectively.