A: Infrared Absorption 197K.

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

C: It responds to the tests for Sodium 191.

Test solution: 10 mg per mL, in water.

100ri / (ris + rc)

0.05 M Phosphate Buffer— Dissolve 7.1 g of anhydrous dibasic sodium phosphate in 1000 mL of water, and adjust with phosphoric acid to a pH of 6.25.

Solution A— Prepare a mixture of 0.05 M Phosphate Buffer and methanol (86:14). Pass through a filter having a porosity of 0.5 µm or less, and degas before use.

Solution B— Prepare a mixture of 0.05 M Phosphate Buffer and methanol (60:40). Pass through a filter having a porosity of 0.5 µm or less, and degas before use.

Mobile phase— Use variable mixtures of Solution A and Solution B as directed for Chromatographic system.

Standard preparation— Transfer about 40 mg of USP Cefotaxime Sodium RS, accurately weighed, to a 50-mL volumetric flask, add about 40 mL of Solution A, swirl to dissolve, dilute with Solution A to volume, and mix. [note—Use this solution promptly. It may be used within 24 hours if stored in the refrigerator.]

Sensitivity solution— Transfer 2.0 mL of Standard preparation to a 100-mL volumetric flask, dilute with Solution A to volume, and mix. Transfer 2.0 mL of this solution to a 20-mL volumetric flask, dilute with Solution A to volume, and mix.

Resolution solution— Mix 1 mL of Standard preparation, 7.0 mL of water, and 2.0 mL of methanol. Add 25 mg of sodium carbonate, mix, and allow to stand at room temperature for 10 minutes, with occasional swirling. Add 3 drops of glacial acetic acid and 1 mL of Standard preparation, and mix.

Assay preparation— Transfer about 40 mg of Cefotaxime Sodium, accurately weighed, to a 50-mL volumetric flask, add Solution A to dissolve it, dilute with Solution A to volume, and mix. [note—Use this solution promptly. It may be used within 24 hours if stored in a refrigerator.]

Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 235-nm detector and a 3.9-mm × 15-cm column that contains 5-µm packing L1 and is maintained at a constant temperature of about 30. The flow rate is about 1 mL per minute. The system is equilibrated with 100% Solution A. Seven minutes after injection of the solution under test, the proportion of Solution B is increased linearly from 0% to 20% at a rate of 10% per minute and is maintained at that composition for 7 minutes. The proportion of Solution B is then increased linearly at a rate of 2.7% per minute until the proportion of Solution B is 100%, and is held at that composition for 5 minutes, after which the proportion of Solution A is increased linearly to 100% at a rate of 20% per minute. Chromatograph the Resolution solution, and record the peak responses as directed under Procedure: the retention times are about 3.5 minutes for desacetylcefotaxime and 14 minutes for cefotaxime, and the resolution, R, between the two peaks is not less than 20. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the retention time for the main cefotaxime peak is between 12 and 15 minutes, the tailing factor is not more than 2, and the relative standard deviation for replicate injections is not more than 1.5%. Chromatograph the Sensitivity solution, and record the peak responses as directed under Procedure: the response of the cefotaxime peak is between 0.18% and 0.22% of the response of the cefotaxime peak in the chromatogram obtained from the Standard preparation.

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 areas for the major peaks. Calculate the quantity, in µg per mg, of cefotaxime (C16H17N5O7S2) in the portion of Cefotaxime Sodium taken by the formula: in which C is the concentration, in mg per mL, of USP Cefotaxime Sodium RS in the Standard preparation; P is the designated content, in µg per mg, of cefotaxime (C16H17N5O7S2) in USP Cefotaxime Sodium RS; W is the weight, in mg, of Cefotaxime Sodium taken to prepare the Assay preparation; and rU and rS are the cefotaxime peak area responses obtained from the Assay preparation and the Standard preparation, respectively.