A: The IRabsorption spectrum of a potassium bromide dispersion of it (about 1mg in 200mg),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 8mg per mL.Dilute 0.1-mLportions of the acetone solutions with 1mLof 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 30minutes,and repeat the test on the residues.

B: The RFvalue of the principal spot in the chromatogram of the Identification preparationcorresponds to that of Standard preparation Aas obtained in the test for Chromatographic purity.

Standard preparations— Dissolve USP Meprobamate RSin alcohol,and mix to obtain Standard preparation Ahaving a known concentration of 1.0mg 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 100mg per mL.

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

Procedure— Apply separately 2µLof the Test preparation,2µLof the Identification preparation,and 2µLof each Standard preparationto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)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 15minutes.Heat the plate at 100for 15minutes,cool,and spray with a solution prepared by dissolving 1g of vanillin in a cooled mixture of sulfuric acid and alcohol (160:40).Heat the plate at 110for 15to 20minutes,cool,and allow the plate to develop blue-purple spots at room temperature.[NOTE—Color development requires approximately 30to 60minutes.]Examine the plate,and compare the intensities of any secondary spots observed in the chromatogram of the Test preparationwith those of the principal spots in the chromatograms of the Standard preparations.No secondary spot from the chromatogram of the Test preparationis 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 preparationcorresponds 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 1.0mg per mL.

Test preparation— Transfer 1.0g of finely powdered Meprobamate,accurately weighed,to a beaker,add 5.0mLof 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 á621ñ)— 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 1mLper 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 50µL)of the Standard preparationand the Test preparationinto the chromatograph,record the chromatograms,and measure the responses for the methyl carbamate peaks:the peak response obtained from the Test preparationis not greater than that obtained from the Standard preparation,corresponding to not more than 0.5%of methyl carbamate.

Solvent— Use dimethyl sulfoxide.