Test specimen— Mix a quantity of ground Tablets, equivalent to about 150 mg of butabarbital sodium, with 1 mL of dimethyl sulfoxide and 1 mL of water, add hydrochloric acid dropwise until the solution is just acid to litmus, and mix. Add 3 g of chromotographic siliceous earth, and mix. Proceed as directed for Column Partition Chromatography under Chromatography 621, packing the chromatographic tube as follows. The lower layer consists of 4 g of chromatographic siliceous earth mixed with 3 mL of sodium carbonate solution (1 in 10), and the upper layer is the test specimen. Wash the column with 75 mL of a water-saturated mixture of isooctane and ether (4:1), and discard the washing. Elute the butabarital with 200 mL of 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 105 for 2 hours.

Medium: water; 900 mL.

Apparatus 1: 100 rpm.

Time: 45 minutes.

Procedure— Determine the amount of C10H15N2NaO3 dissolved from UV absorbances at the wavelength of maximum absorbance at about 239 nm on filtered portions of the solution under test, mixed with sufficient ammonium hydroxide to provide a concentration of 0.5 N ammonium hydroxide, and suitably diluted with Medium, if necessary, in comparison with a Standard solution having a known concentration of USP Butabarbital RS in the same medium.

Tolerances— Not less than 75% (Q) of the labeled amount of C10H15N2NaO3 is dissolved in 45 minutes.

Change to read:

Procedure for content uniformity—

Acid–methanol mixture— Prepare a mixture of methanol and 1 N hydrochloric acid (9:1).

Standard preparation— Dissolve an accurately weighed quantity of USP Butabarbital RS in Acid–methanol mixture to obtain a solution having a known concentration of about 0.45 mg per mL.USP29

Test preparation— Transfer 1 finely powdered Tablet to a 25-mL volumetric flask, add Acid–methanol mixture to volume, and mix. Filter, discarding the first 5 mL of the filtrate, and dilute the subsequent filtrate, quantitatively and stepwise if necessary, with Acid–methanol mixture to obtain a solution containing 0.5 to 0.6 mg of butabarbital sodium per mL.USP29

Procedure— Transfer 2.0 mL each of the Standard preparation and the Test preparation to separate 100-mL volumetric flasks, and transfer 2.0 mL of Acid–methanol mixture to a third volumetric flask to provide a blank. Dilute each flask with pH 9.6 alkaline borate buffer (see under Solutions in the section Reagents, Indicators, and Solutions), and mix. Concomitantly determine the absorbances of the solutions in 1-cm cells at the wavelength of maximum absorbance at about 240 nm, with a suitable spectrophotometer, using the blank to set the instrument.USP29 Calculate the quantity, in mg, of C10H15N2NaO3 in the Tablet takenUSP29 by the formula: USP29in which 234.23 and 212.25 are the molecular weights of butabarbital sodium and butabarbital, respectively; T is the labeled quantity, in mg, of butabarbital sodium in the Tablet; C is the concentration, in mgUSP29 per mL, of USP Butabarbital RS in the Standard preparation; D is the concentration, in mgUSP29 per mL, of butabarbital sodium in the Test preparation, based upon the labeled quantity per Tablet and the extent of dilution; and AU and AS are the absorbances of the solutions from the Test preparation and the Standard preparation, respectively.

(Official January 1, 2007)

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 1.2 mg per mL.

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

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

Chromatographic system and System suitability— Proceed as directed for Chromatographic System and System Suitability under Barbiturate Assay 361. The resolution, R, between butabarbital and secobarbital is not less than 2.4; and the relative retention times are approximately 0.6 for butabarbital and 1.0 for secobarbital.

Procedure— Proceed as directed for Procedure under Barbiturate Assay 361. Calculate the quantity, in mg, of C10H15N2NaO3 in the portion of Tablets taken by the formula: in which 234.23 and 212.25 are the molecular weights of butabarbital sodium and butabarbital, respectively; and the other terms are as defined therein.