Mobile phaseand Chromatographic system— Proceed as directed in the Assayunder Piperacillin.

Standard piperacillin solution— Proceed as directed in the Related compounds,Test 1under Piperacillin.

Test solution 1and Test solution 2— Use Assay preparation 1and Assay preparation 2,respectively,and proceed as directed under the Assay.

Procedure— Separately inject equal volumes (about 10µL)of the Test solutionsand the Standard piperacillin solution,and proceed as directed in the Assay.Calculate the percentage of piperacillin related compound Aand piperacillin related compound Cin the portion of Piperacillin for Injection taken by the formula: in which Cis the concentration,in mg per mL,of USP Piperacillin RSin the Standard piperacillin solution,Pis the designated potency,in µg of piperacillin per mg,of USP Piperacillin RS,Ais the quantity,in mg,of piperacillin in each mLof Test solution 1or Test solution 2,RRFiis the response factor of an individual piperacillin related compound relative to the response of piperacillin,specifically 1.4for piperacillin related compound Aand 0.93for piperacillin related compound C,riis the response of each impurity peak,if any,observed in the chromatogram of the Test solutionat a retention time corresponding to piperacillin related compound Aor piperacillin related compound C,and rSp is the peak response of the piperacillin peak in the chromatogram of the Standard piperacillin solution:not more than 3.5%of piperacillin related compound Aand not more than 1.0%of piperacillin related compound Cis found.

Mobile phase,Standard preparation,Resolution solution,and Chromatographic system— Proceed as directed in the Assayunder Piperacillin.

Assay preparation 1 (where it is labeled for use as a single-dose container)—Constitute Piperacillin 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 Mobile phaseto obtain a solution containing about 0.4mg of piperacillin per mL.

Assay preparation 2 (where the label states the quantity of piperacillin in a given volume of the constituted solution)—Constitute Piperacillin for Injection in 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 with Mobile phaseto obtain a solution containing about 0.4mg of piperacillin per mL.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationsinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg of piperacillin (C23H27N5O7S)in the container,or in the portion of constituted solution taken by the formula: in which Lis the labeled quantity,in mg,of piperacillin in the container or in the volume of constituted solution taken,Dis the concentration,in mg of piperacillin per mL,of Assay preparation 1or Assay preparation 2,based on the labeled quantity in the container or in the portion of constituted solution taken,respectively,and the extent of dilution,Cis the concentration,in mg per mL,of USP Piperacillin RSin the Standard preparation,Pis the designated potency,in µg of piperacillin per mg,of USP Piperacillin RS,and rUand rSare the piperacillin peak responses obtained from the Assay preparationand the Standard preparation,respectively.