A:Infrared Absorption á197Kñ —Prepare the test specimen as follows.Transfer about 150mg to a suitable separator,dissolve in 10mLof water,and add 15mLof 3Nhydrochloric acid.Extract with three 20-mLportions of chloroform,filter the extracts through anhydrous sodium sulfate,and collect the extracts in a suitable beaker.Evaporate the combined chloroform extracts on a steam bath with the aid of a current of air to dryness,and dry the residue at 105for 2hours.

B:UltravioletAbsorption á197Uñ—

C: Ignite about 100mg:the residue responds to the tests for Sodium á191ñ.

Standard solutions— Dissolve a quantity of USP Butabarbital RSin a mixture of chloroform and methanol (1:1)to obtain a solution having a final concentration of 4.0mg per mL(Standard solution A).Dilute 1.0mLof Standard solution Awith a mixture of chloroform and methanol (1:1)to 10.0mL,and mix (Standard solution B).

Test solution —Dissolve a quantity of Butabarbital Sodium in a mixture of chloroform and methanol (1:1)to obtain a solution having a final concentration of 44mg per mL.

Procedure —Apply 10µLof the Test solutionand 10µLeach of Standard solution Aand Standard solution Bto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.Develop the chromatogram in a solvent system consisting of a mixture of acetone,methylene chloride,methanol,and ammonium hydroxide (5:3:1:1)until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the developing chamber,and dry the plate in a current of air.Spray the plate with a solution of mercurous nitrate dihydrate in 0.15Nnitric acid (1in 100),and immediately estimate the intensities of any spots in the chromatogram of the Test solution,other than the principal spot,in comparison with Standard solution B:the RFvalue of the principal spot obtained from the Test solutioncorresponds to that obtained from Standard solution A;and the sum of the intensities of any secondary spots observed in the chromatogram of the Test solutionis not greater than the intensity of the principal spot produced by Standard solution B,corresponding to not more than a total of 1%of impurities.

Standard preparation— Transfer about 25mg of USP Butabarbital RS,accurately weighed,to a 200-mLvolumetric flask,dissolve in pH9.6alkaline borate buffer (see under Buffer Solutionsin the section Reagents,Indicators,and Solutions),and dilute with the same solvent to volume.

Assay preparation —Transfer about 28mg of Butabarbital Sodium,accurately weighed,to a 200-mLvolumetric flask,dissolve in pH9.6alkaline borate buffer to volume,and dilute with the same solvent to volume.

Procedure— Transfer 10.0mLeach of the Standard preparationand the Assay preparationto separate 100-mLvolumetric flasks,dilute each with pH9.6alkaline borate buffer to volume,and mix.Concomitantly determine the absorbances of the solutions at the wavelength of maximum absorbance at about 240nm,with a suitable spectrophotometer,using pH9.6alkaline borate buffer as the blank.Calculate the quantity,in mg,of C10H15N2NaO3in the portion of Butabarbital Sodium taken by the formula: in which 234.23and 212.25are the molecular weights of butabarbital sodium and butabarbital,respectively;Cis the concentration,in µg per mL,of USP Butabarbital RSin the Standard preparation;and AUand ASare the absorbances of the solutions from the Assay preparationand the Standard preparation,respectively.