Mobile phase,Standard preparation,Resolution solution,andChromatographic system— Prepare as directed for the Assayunder Mezlocillin Sodium.

Assay preparation 1 (where it is represented as being in a single-dose container)—Constitute Mezlocillin 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 with water to obtain a solution containing about 0.5mg of mezlocillin per mL.

Assay preparation 2 (where the label states the quantity of mezlocillin in a given volume of constituted solution)—Constitute Mezlocillin for Injection in a volume of water,accurately measured,corresponding to the volume of solvent specified in the labeling.Dilute an accurately measured portion of the constituted solution quantitatively with water to obtain a solution containing about 0.5mg of mezlocillin per mL.

Procedure— [NOTE—Use peak areas where peak responses are indicated.]Separately inject equal volumes (about 20µL)of the Standard preparationand Assay preparation 1into the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of mezlocillin in the container,or in the portion of constituted solution taken by the formula: in which Lis the labeled quantity,in mg,of mezlocillin in the container,or in the volume of constituted solution taken,Dis the concentration,in mg per mL,of mezlocillin in Assay preparation 1or in Assay preparation 2,on the basis of the labeled quantity in the container,or in the portion of constituted solution taken,respectively,and the extent of dilution,Cis the concentration,in µg per mL,of mezlocillin (C21H25N5O8S2)in the Standard preparation,and rUand rSare the mezlocillin peak responses obtained from the Standard preparationand from Assay preparation 1or Assay preparation 2,as appropriate.