Test specimen— Proceed as directed in the chapter, but do not dry.

Mobile phase— Prepare a filtered and degassed mixture of 0.01 N nitric acid and acetonitrile (100:1). Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard solution— Transfer about 0.16 mL of N-methylpyrrolidine, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with water to volume, and mix. Transfer 4.0 mL of this solution to a 100-mL volumetric flask, dilute with 0.01 N nitric acid to volume, and mix. This solution contains about 0.05 mg of N-methylpyrrolidine per mL.

Test solution— Transfer about 100 mg of Cefepime Hydrochloride, accurately weighed, to a 10-mL volumetric flask, dissolve in and dilute with 0.01 N nitric acid to volume, and mix. [NOTE—Use this solution within 30 minutes.]

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a conductivity detector and a 4.6-mm × 5-cm column that contains 5-µm packing L52. The flow rate is about 1 mL per minute. Chromatograph the Standard solution, and record the peak responses as directed for Procedure: the retention time of N-methylpyrrolidine is not less than 8 minutes, and the relative standard deviation for replicate injections is not more than 5.0%.

Procedure— Separately inject equal volumes (about 100 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the peak responses for N-methylpyrrolidine. Calculate the percentage of N-methylpyrrolidine in the portion of Cefepime Hydrochloride taken by the formula: in which C is the concentration, in mg per mL, of N-methylpyrrolidine in the Standard solution; W is the quantity, in mg, of Cefepime Hydrochloride taken to prepare the Test solution; and rU and rS are the N-methylpyrrolidine peak responses obtained from the Test solution and the Standard solution, respectively: not more than 0.3% is found.

Potassium phosphate solution— Dissolve 0.68 g of monobasic potassium phosphate in 1000 mL of water.

Solution A— Prepare a mixture of Potassium phosphate solution and acetonitrile (9:1). Adjust with a potassium hydroxide solution (2 in 100) to a pH of 5.0, filter, and degas.

Solution B— Prepare a mixture of Potassium phosphate solution and acetonitrile (1:1). Adjust with a potassium hydroxide solution (2 in 100) to a pH of 5.0, filter, and degas.

Mobile phase— Use variable mixtures of Solution A and Solution B as directed for Chromatographic system. Make adjustments if necessary (see System Suitability under Chromatography 621).

System suitability solution— Prepare a solution of USP Cefepime Hydrochloride System Suitability RS in Solution A containing about 1.4 mg per mL.

Test solution— Transfer about 70 mg of Cefepime Hydrochloride, accurately weighed, to a 50-mL volumetric flask, dissolve in and dilute with Solution A to volume, sonicate, and mix. [NOTE—Inject this solution immediately, or store in a refrigerator and inject within 12 hours.]

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm × 25-cm column that contains 5-µm packing L1. The flow rate is about 1 mL per minute. The chromatograph is programmed as follows. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the relative retention times are about 2.7 for cefepime related compound A, 4.3 for cefepime related compound B, and 1.0 for cefepime; and the resolution, R, between cefepime and cefepime related compound A is not less than 5 and between cefepime related compound A and cefepime related compound B is not less than 10. Chromatograph the Test solution, and record the peak responses as directed for Procedure: the capacity factor, k¢, is more than 0.6; the column efficiency is not less than 4000 theoretical plates; and the tailing factor is not more than 1.1.

Procedure— Inject a volume (about 10 µL) of the Test solution into the chromatograph, record the chromatogram, and measure the peak responses. Calculate the percentage of each impurity in the portion of Cefepime Hydrochloride taken by the formula: in which ri is the peak response for each impurity; and rs is the sum of the responses for all the peaks: not more than 0.3% of cefepime related compound A is found; not more than 0.2% of cefepime related compound B is found; and not more than 0.1% of any other impurity is found.

(Official January 1, 2007)

Mobile phase— Dissolve 5.76 g of sodium 1-pentanesulfonate in 2000 mL of water. Adjust with glacial acetic acid to a pH of 3.4, and then with potassium hydroxide TS to a pH of 4.0. Prepare a filtered and degassed mixture of this solution and acetonitrile (94:6). Make adjustments if necessary (see System Suitability under Chromatography 621).

Standard preparation— Dissolve an accurately weighed quantity of USP Cefepime Hydrochloride RS in Mobile phase to obtain a solution having a known concentration of about 1.4 mg per mL.

Assay preparation— Transfer about 70 mg of Cefepime Hydrochloride, accurately weighed, to a 50-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm × 30-cm column that contains packing L1. The flow rate is about 2 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the column efficiency is not less than 1500 theoretical plates; the tailing factor is not more than 1.7; and the relative standard deviation for replicate injections is not more than 2.0%.

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 cefepime (C19H24N6O5S2) in each mg of Cefepime Hydrochloride taken by the formula: in which C is the concentration, in mg per mL, of USP Cefepime Hydrochloride RS in the Standard preparation; P is the content, in µg per mg, of cefepime in USP Cefepime Hydrochloride RS; W is the weight, in mg, of Cefepime Hydrochloride taken to prepare the Assay preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.