Assay
Dissolve the contents of 10containers of Thiopental Sodium for Injection in sufficient water,diluting to an accurately measured volume,to obtain a solution containing about 50mg of thiopental sodium per mL.Dilute this solution quantitatively and stepwise with sodium hydroxide solution (1in 250)to obtain a solution having a concentration of about 5µg of thiopental sodium per mL.Proceed as directed in the
Assayunder
Thiopental Sodium,beginning with Dissolve an accurately weighed quantity of
USP Thiopental RS.Calculate the average quantity,in mg,of C
11H
17N
2NaO
2Sin each container of Thiopental Sodium for Injection taken by the formula:
VC(1.091AU/AS),
in which
Vis the volume,in mL,of the solution prepared to contain about 50mg of thiopental sodium per mL,
Cis the concentration,in µg per mL,of
USP Thiopental RSin the Standard solution,1.091is the ratio of the molecular weight of thiopental sodium to that of thiopental,and
AUand
ASare the absorbances of the solution of Thiopental Sodium for Injection and the Standard solution,respectively.