Mobile phase, Standard preparation, Resolution solution, and Chromatographic system— Prepare as directed for the Assay under 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 0.5 mg 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 0.5 mg of mezlocillin per mL.

Procedure— [note—Use peak areas where peak responses are indicated.] Separately inject equal volumes (about 20 µL) of the Standard preparation and Assay preparation 1 into 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 L is the labeled quantity, in mg, of mezlocillin in the container, or in the volume of constituted solution taken, D is the concentration, in mg per mL, of mezlocillin in Assay preparation 1 or 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, C is the concentration, in µg per mL, of mezlocillin (C21H25N5O8S2) in the Standard preparation, and rU and rS are the mezlocillin peak responses obtained from the Standard preparation and from Assay preparation 1 or Assay preparation 2, as appropriate.