Procedure for content uniformity— Perform the Assayon individual containers using Assay preparation 1or Assay preparation 2,or both,as appropriate.

Mobile phase ,Standard preparation,and Chromatographic system—Proceed as directed in the Assayunder Oxacillin Sodium.

Assay preparation 1 (where it is represented as being in a single-dose container)—Constitute Oxacillin for Injection in a volume of water,accurately measured,corresponding to the volume of solvent specified in the labeling.Withdraw all of the withdrawable contents using a suitable hypodermic needle and syringe,and dilute quantitatively,and stepwise if necessary,with water to obtain a solution containing about 0.1mg per mLof oxacillin.[NOTE—Use this solution on the day prepared.]

Assay preparation 2 (where the label states the quantity of oxacillin in a given volume of constituted solution)—Constitute Oxacillin for Injection with a volume of water,accurately measured,corresponding to the volume of solvent specified in the labeling.Dilute an accurately measured volume of the constituted solution quantitatively,and stepwise if necessary,with water to obtain a solution containing about 0.1mg per mLof oxacillin (C19H19N3O5S).[NOTE—Use this solution on the day prepared.]

Procedure— Proceed as directed in the Assayunder Oxacillin Sodium.Calculate the quantity,in mg,of oxacillin (C19H19N3O5S)in the constituted solution taken by the formula: in which Lis the labeled quantity,in mg,of oxacillin in the container or in the volume of constituted solution taken;Dis the concentration,in mg per mL,of oxacillin in Assay preparation 1or in Assay preparation 2,on the basis of the labeled quantity in the container or in the volume of constituted solution taken,respectively;Cis the concentration,in mg per mL,of USP Oxacillin Sodium RSin the Standard preparation;Eis the oxacillin equivalent,in µg per mg,of USP Oxacillin Sodium RS;and rUand rSare the oxacillin peak responses obtained from the Assay preparationand the Standard preparation,respectively.Where the test for Uniformity of dosage unitshas been performed using the Procedure for content uniformity,use the average of these determinations as the Assayvalue.