A: Infrared Absorption 197F.

B: Dissolve about 1 g in 20 mL of methanol. To 1 mL of the solution, add about 4 drops of 6 N ammonium hydroxide, mix, then add silver nitrate TS, a few drops at a time: a yellowish white precipitate is formed, and it at first redissolves, but becomes insoluble when an excess of silver nitrate TS has been added.

C: To 10 mL of the solution prepared in Identification test B add 5 mL of freshly prepared m-phenylenediamine hydrochloride-oxalic acid solution (prepared by dissolving 1 g of m-phenylenediamine hydrochloride and 1 g of oxalic acid in 35 mL of water and filtering, if necessary): a reddish orange color is produced in about 3 minutes.

100ri / rt

Resolution solution— Add 2.5 µL of toluene to 0.5 mL of USP Ethchlorvynol RS, and mix.

Chromatographic system (see Chromatography 621)—The gas chromatograph is equipped with a thermal conductivity 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 Resolution solution, and record the peak responses as directed for Procedure: the relative retention times for toluene, -chlorovinylethyl ketone (if present), Z-ethchlorvynol, and E-ethchlorvynol are about 0.1, 0.2, 0.8, and 1.0, respectively; the resolution, R, between the Z- and E-ethchlorvynol peaks is not less than 1.0; and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— [note—Use peak areas where peak responses are indicated.] Inject about 3 µL of Ethchlorvynol into the chromatograph, record the chromatogram, and measure the responses for all of the peaks. Calculate the percentage of E-ethchlorvynol (C7H9ClO) in the specimen of Ethchlorvynol taken by the formula: in which re is the response of the E-ethchlorvynol peak obtained in the chromatogram of the Ethchlorvynol and rt is the sum of the responses of all of the peaks observed in the chromatogram.