A: Suspend the contents of 1Capsule in 10mLof water,and filter:the filtrate responds to the flame test for Sodium á191ñ.

B: The retention times of the major peaks in the chromatogram of the Assay preparationcorrespond to those of the Standard preparationobtained in the Assay.

Medium: water;500mL.

Apparatus 1: 100rpm.

Time: 60minutes.

Procedure— Determine the total amount of C12H17N2NaO3and C11H17N2NaO3dissolved from UVabsorbances at the wavelength of maximum absorbance at about 239nm of filtered portions of the solution under test,suitably diluted with 0.1Nsodium hydroxide,in comparison with a Standard solution having known concentrations of about 7.5µg each per mL,of USP Secobarbital RSand USP Amobarbital RSin the same medium.An amount of alcohol not to exceed 1%of the total volume of the Standard solution may be used to dissolve the Reference Standards prior to dilution with water and 0.1Nsodium hydroxide.

Tolerances— Not less than 60%(Q)of the labeled total amount of C12H17N2NaO3and C11H17N2NaO3is dissolved in 60minutes.

Internal standard solution— Dissolve aprobarbital in chloroform to obtain a solution having a concentration of about 0.75mg per mL.

Standard preparation— Transfer about 92mg of USP Secobarbital RS,and about 91mg of USP Amobarbital RS,both accurately weighed,to a 100-mLvolumetric flask,and dissolve in 50mLof chloroform.Dilute with chloroform to volume,and mix.

Assay preparation— Remove,as completely as possible,the contents of not less than 20Capsules.Transfer an accurately weighed portion of the powder,equivalent to about 100mg of secobarbital sodium,to a separator,add 20mLof water,1mLof hydrochloric acid,and 100.0mLof chloroform,and shake for 3minutes.Remove the chloroform layer,and use as directed in the Procedure.

Chromatographic system (see Chromatography á621ñ)—The gas chromatograph is equipped with a flame-ionization detector and contains a 0.6-m ×3.5-mm glass column packed with 3percent liquid phase G10on 100-to 120-mesh support S1AB.The column is maintained at about 175,the injection port at about 235,the detector block at about 245,and dry helium is used as the carrier gas at a flow rate of about 55mLper minute.Chromatograph five replicate injections of the Standard preparation,and record the peak responses as directed for Procedure:the relative standard deviation is not more than 2%;the resolution factor between amobarbital and the internal standard is not less than 1.5;the resolution factor between amobarbital and secobarbital is not less than 2.5;and the tailing factor does not exceed 1.5for any of the three peaks.

Procedure— Mix 5.0mLof the Standard preparationwith 5.0mLof the Internal standard solution.Mix 5.0mLof the Assay preparationwith 5.0mLof the Internal standard solution.Separately inject equal volumes (about 3µL)of the resulting solutions into the chromatograph,and record the chromatograms.Measure the responses for the major peaks.The relative retention times with respect to the internal standard are about 1.3for amobarbital and 1.8for secobarbital.Calculate the quantity,in mg,of secobarbital sodium (C12H17N2NaO3)in the portion of Capsules taken by the formula: in which 260.27and 238.28are the molecular weights of secobarbital sodium and secobarbital,respectively,Wis the weight,in mg,of USP Secobarbital RStaken for the Standard preparation,and RUand RSare the ratios of the peak response of secobarbital to that of the internal standard in the Assay preparationand the Standard preparation,respectively.Similarly calculate the quantity,in mg,of amobarbital sodium (C11H17N2NaO3)in the portion of Capsules taken by the formula: in which 248.26and 226.28are the molecular weights of amobarbital sodium and amobarbital,respectively,W¢is the weight,in mg,of USP Amobarbital RStaken for the Standard preparation,and R¢Uand R¢Sare the ratios of the peak response of amobarbital to that of the internal standard obtained from Assay preparationand the Standard preparation,respectively.