A: The chromatogram obtained from the Assay preparation in the Assay exhibits a major peak for piperacillin, the retention time of which corresponds to that exhibited by the Standard preparation, and the chromatogram compares qualitatively to that obtained from the Standard preparation.

B: It responds to the tests for Sodium 191.

Mobile phase and Chromatographic system— Proceed as directed in the Assay under Piperacillin.

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

Test solution— Use the Assay preparation.

Procedure— Separately inject equal volumes (about 10 µL) of the Test solution and the Standard piperacillin and proceed as directed in the Assay. Calculate the percentage of piperacillin related compound A and piperacillin related compound C in the portion of Piperacillin Sodium taken by the formula: in which C is the concentration, in mg per mL, of USP Piperacillin RS in the Standard piperacillin solution, P is the designated potency, in µg of piperacillin per mg, of USP Piperacillin RS, W is the weight, in mg, of Piperacillin Sodium taken to prepare the Test solution, RRFi is the response factor of an individual piperacillin related compound relative to the response of piperacillin, specifically 1.4 for piperacillin related compound A and 0.93 for piperacillin related compound C, ri is the response of the impurity peak, if any, observed in the chromatogram of the Test solutionat a retention time corresponding to piperacillin related compound A or 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 A and not more than 1.0% of piperacillin related compound C is found.

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

Assay preparation— Transfer about 20 mg of Piperacillin Sodium, accurately weighed, to a 50-mL volumetric flask. Add about 35 mL of Mobile phase, and shake to dissolve. Dilute with Mobile phase to volume, and mix.

Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the potency, in µg of piperacillin (C23H27N5O7S) per mg, of the portion of Piperacillin Sodium taken by the formula: in which C is the concentration, in mg per mL, of USP Piperacillin RS in the Standard preparation, P is the designated potency, in µg of piperacillin per mg, of USP Piperacillin RS, W is the weight, in mg, of Piperacillin Sodium taken to prepare the Assay preparation, and rU and rS are the piperacillin peak responses obtained from the Assay preparation and the Standard preparation, respectively.