A: The IR absorption spectrum of a potassium bromide dispersion of it (about 1 mg in 200 mg), previously dried, exhibits maxima only at the same wavelengths as that of a similar preparation of USP Meprobamate RS. If a difference appears, dissolve portions of both the test specimen and the Reference Standard in acetone at a concentration of 8 mg per mL. Dilute 0.1-mL portions of the acetone solutions with 1 mL of n-heptane, and remove the solvents by evaporation under nitrogen at a temperature of about 30. Dry the residues in vacuum at room temperature for 30 minutes, and repeat the test on the residues.

B: The RF value of the principal spot in the chromatogram of the Identification preparation corresponds to that of Standard preparation A as obtained in the test for Chromatographic purity.

Standard preparations— Dissolve USP Meprobamate RS in alcohol, and mix to obtain Standard preparation A having a known concentration of 1.0 mg per mL. Dilute quantitatively with alcohol to obtain Standard preparations, designated below by letter, having the following compositions:

Test preparation— Dissolve an accurately weighed quantity of Meprobamate in alcohol to obtain a solution containing 100 mg per mL.

Identification preparation— Dilute a portion of the Test preparation quantitatively with alcohol to obtain a solution containing 1.0 mg per mL.

Procedure— Apply separately 2 µL of the Test preparation, 2 µL of the Identification preparation, and 2 µL of each Standard preparation to a suitable thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel. Position the plate in a chromatographic chamber, and develop the chromatograms in a solvent system consisting of a mixture of hexane, acetone, and pyridine (7:3:1) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and air-dry the plate for 15 minutes. Heat the plate at 100 for 15 minutes, cool, and spray with a solution prepared by dissolving 1 g of vanillin in a cooled mixture of sulfuric acid and alcohol (160:40). Heat the plate at 110 for 15 to 20 minutes, cool, and allow the plate to develop blue-purple spots at room temperature. [note—Color development requires approximately 30 to 60 minutes.] Examine the plate, and compare the intensities of any secondary spots observed in the chromatogram of the Test preparation with those of the principal spots in the chromatograms of the Standard preparations. No secondary spot from the chromatogram of the Test preparation is larger or more intense than the principal spot obtained from Standard preparation A (1.0%), and the sum of the intensities of all secondary spots obtained from the Test preparation corresponds to not more than 2.0%.

Mobile phase— Use filtered and degassed water.

Standard preparation— Dissolve an accurately weighed quantity of methyl carbamate in water to obtain a solution having a known concentration of 1.0 mg per mL.

Test preparation— Transfer 1.0 g of finely powdered Meprobamate, accurately weighed, to a beaker, add 5.0 mL of water, and stir to wet the powder completely. Filter the slurry through a small plug of glass wool in the stem of a glass funnel. Use the clear filtrate as the Test preparation.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 200-nm detector and a 3.9- to 4.6-mm × 25- to 30-cm column that contains packing L1. The flow rate is about 1 mL per minute. Chromatograph replicate injections of the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation is not more than 2.0%.

Procedure— Separately inject equal volumes (about 50 µL) of the Standard preparation and the Test preparation into the chromatograph, record the chromatograms, and measure the responses for the methyl carbamate peaks: the peak response obtained from the Test preparation is not greater than that obtained from the Standard preparation, corresponding to not more than 0.5% of methyl carbamate.