A: The chromatogram of the Assay preparation obtained as directed in the Assay exhibits a major peak for cefonicid, the retention time of which corresponds to that exhibited in the chromatogram of the Standard preparation, as obtained in the Assay.

B: It responds to the tests for Sodium 191.

Test solution: 10 mg per mL, in methanol.

Mobile phase— Prepare a mixture of water, methanol, and 0.2 M monobasic ammonium phosphate (33:5:2). Pass through a filter having a 0.5-µm or finer porosity, and degas. Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard preparation— Dissolve an accurately weighed quantity of USP Cefonicid Sodium RS in Mobile phase to obtain a solution having a known concentration of about 200 µg of cefonicid (C18H18N6O8S3) per mL.

Assay preparation— Transfer about 40 mg of Cefonicid Sodium, accurately weighed, to a 200-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.

Resolution solution— Dissolve a quantity of USP Cefonicid Sodium RS in Mobile phase to obtain a solution containing about 0.2 mg per mL. Heat on a steam bath for 30 minutes, and cool. This Resolution solution contains a mixture of cefonicid and desacetyl cefonicid.

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 254-nm detector and a 4-mm × 30-cm column that contains packing L1. The flow rate is about 2 mL per minute. Chromatograph the Standard preparation and the Resolution solution, and record the peak responses as directed for Procedure: the resolution R, between the cefonicid and the desacetyl cefonicid peaks is not less that 1.1; the column efficiency determined from the analyte peak is not less than 1500 theoretical plates; the tailing factor for the analyte peak is not more than 2.0; and the relative standard deviation for replicate injections of the Standard preparation is not more than 2%.

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 quantity, in µg, of cefonicid (C18H18N6O8S3) per mg of the Cefonicid Sodium taken by the formula: in which C is the concentration, in µg per mL of cefonicid (C18H18N6O8S3) in the Standard preparation; M is the quantity, in mg, of Cefonicid Sodium taken to prepare the Assay preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.