Test specimen— Mix a quantity of ground tablets,equivalent to about 150mg of butabarbital sodium,with 1mLof dimethylsulfoxide and 1mLof water,add hydrochloric acid dropwise until the solution is just acid to litmus,and mix.Add 3g of chromotographic siliceous earth,and mix.Proceed as directed for Column Partition Chromatographyunder Chromatography á621ñ,packing the chromatographic tube as follows.The lower layer consists of 4g of chromatographic siliceous earth mixed with 3mLof sodium carbonate solution (1in 10),and the upper layer is the test specimen.Wash the column with 75mLof a water-saturated mixture of isooctane and ether (4:1),and discard the washing.Eluate the butabaritol with 200mLof water-saturated ether,collecting the eluate in a suitable vessel.Evaporate the eluate to dryness on a steam bath under a current of air,and dry the residue at 105for 2hours.

Medium: water;900mL.

Apparatus 1: 100rpm.

Time: 45minutes.

Procedure— Determine the amount of C10H15N2NaO3dissolved from UVabsorbances at the wavelength of maximum absorbance at about 239nm of filtered portions of the solution under test,mixed with sufficient ammonium hydroxide to provide a concentration of 0.5Nammonium hydroxide,and suitably diluted with Dissolution Medium,if necessary,in comparison with a Standard solution having a known concentration of USP Butabarbital RSin the same medium.

Tolerances— Not less than 75%(Q)of the labeled amount of C10H15N2NaO3is dissolved in 45minutes.

Procedure for content uniformity—

Acid-methanol mixture and Standard preparation—Prepare as directed in the test for Content uniformityunder Butabarbital Sodium Capsules.

Test preparation— Transfer 1finely powdered Tablet to a 25-mLvolumetric flask,and proceed as directed for Test preparationin the test for Content uniformityunder Butabarbital Sodium Capsules,beginning with “add Acid-methanol mixtureto volume.”

Procedure— Proceed as directed for Procedurein the test for Content uniformityunder Butabarbital Sodium Capsules.Calculate the quantity,in mg,of C10H15N2NaO3in the Tablet by the formula given therein,in which 234.23and 212.25are the molecular weights of butabarbital sodium and butabarbital,respectively;Tis the labeled quantity,in mg,of butabarbital sodium in the Tablet;Cis the concentration,in µg per mL,of USP Butabarbital RSin the Standard preparation;Dis the concentration,in µg per mL,of butabarbital sodium in the Test preparation,based upon the labeled quantity per Tablet and the extent of dilution;and AUand ASare the absorbances of the solutions from the Test preparationand the Standard preparation,respectively.

Internal standard solution— Dissolve an accurately weighed quantity of secobarbital in chloroform,and dilute quantitatively with chloroform to obtain a solution having a known concentration of about 1.2mg per mL.

Standard preparation— Dissolve accurately weighed quantities of USP Butabarbital RSand secobarbital in chloroform,and dilute quantitatively with chloroform to obtain a solution that contains,in each mL,known amounts of about 0.8mg of USP Butabarbital RSand about 1mg of secobarbital.

Assay preparation— Weigh and finely powder not less than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 50mg of butabarbital sodium,to a 50-mLvolumetric flask,add 35mLof dilute ammonium hydroxide (1in 25),dilute with water to volume,and mix.Filter,if necessary,discarding the first 15mLof the filtrate,and transfer 25.0mLof the clear solution to a separator.Add 2mLof hydrochloric acid,and extract with three 25-mLportions of chloroform.Filter the extracts through about 15g of anhydrous sodium sulfate that is supported on a funnel by a small pledget of glass wool.Collect the combined filtrate in a 100-mLvolumetric flask,wash the sodium sulfate with 15mLof chloroform,collecting the washing with the filtrate,dilute with chloroform to volume,and mix.Combine 4.0mLof this solution with 1.0mLof Internal standard solutionin a suitable container,and reduce the volume to about 1mLby evaporation,with the aid of a stream of dry nitrogen,at room temperature.

Chromatographic system and System suitability—Proceed as directed for Chromatographic Systemand System Suitabilityunder Barbiturate Assay á361ñ.The resolution,R,between butabarbital and secobarbital is not less than 2.4;and the relative retention times are approximately 0.6for butabarbital and 1.0for secobarbital.

Procedure— Proceed as directed for Procedureunder Barbiturate Assay á361ñ.Calculate the quantity,in mg,of C10H15N2NaO3in the portion of Tablets taken by the formula: in which 234.23and 212.25are the molecular weights of butabarbital sodium and butabarbital,respectively;and the other terms are as defined therein.