A: Infrared Absorption á197Mñ.

B: Ultraviolet Absorption á197Uñ—

C: Dissolve 1mg of it in 4mLof water,add 1mLof 1Nsulfuric acid while cooling in an ice bath,add 1mLof a freshly prepared solution of sodium nitrite (1in 100),allow to stand for 2minutes,then add 1mLof ammonium sulfamate solution (1in 100).Allow to stand for 1minute,and add 1mLof N-(1-naphthyl)ethylenediamine dihydrochloride TS:a red-purple color develops.

Test solution: 10mg per mL,in methanol.

Change to read:

Solution A— Prepare filtered and degassed 0.02Mammonium acetate.

Solution B— Use filtered and degassed acetonitrile.

Mobile phase— Use variable mixtures of Solution Aand Solution Bas directed for Chromatographic system.Make adjustments if necessary (see System SuitabilityunderChromatography á621ñ).

Diluent— Prepare a degassed mixture of water and acetonitrile (2:1).

System suitability solution— Dissolve a quantity of USP Cefpodoxime Proxetil RSin Diluentto obtain a solution containing about 10µg per mL.[NOTE—Avolume of methanol not exceeding 10%of the total volume in the final solution may be used to facilitate dissolution.]

Test solution— Transfer about 50mg of Cefpodoxime Proxetil,accurately weighed,to a 50-mLvolumetric flask,dissolve in 5mLof methanol,using sonication if necessary,dilute with Diluentto volume,and mix.This solution should be injected promptly,but may be analyzed within 24hours when stored at 8.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 260-nm detector and a 4.6-mm ×25-cm column that contains 5-µm packing L1.The column temperature is maintained at a constant temperature of about 30.The flow rate is about 2mLper minute.The chromatograph is programmed as follows. Chromatograph the System suitability solution,and record the peak responses as directed for Procedure:the retention time for cefpodoxime proxetil R-epimer is between 37and 42minutes;the relative retention times are about 0.9for cefpodoxime proxetil S-epimer and 1.0for cefpodoxime proxetil R-epimer;the resolution,R,between cefpodoxime proxetil S-epimer and cefpodoxime proxetil R-epimer is not less than 4.0;the column efficiency is not less than 19,000theoretical plates determined from the cefpodoxime proxetil R-epimer peak;and the relative standard deviation for replicate injections determined from the sum of the areas of the cefpodoxime proxetil S-epimer and cefpodoxime proxetil R-epimer peaks is not more than 2.0%.

Procedure— Inject a volume (about 20µL)of the Test solutioninto the chromatograph,record the chromatogram,and measure all of the peak areas.Calculate the percentage of each impurity in the portion of Cefpodoxime Proxetil taken by the formula: in whichriis the peak area for each impurity;andrsis the sum of the areas of all the peaks:not more than 3.0%of any peak at a relative retention time of about 0.86is found;not more than 1.0%for any peak at relative retention times of about 1.27,1.39,and other individual peaks having relative retention times higher than 2.0is found;not more than 0.5%of any other individual impurity is found;and not more than 6.0%of total impurities is found,impurity peaks of less than 0.05%being disregarded.

Mobile phase— Prepare a filtered and degassed mixture of 0.02Mammonium acetate and acetonitrile (6:4).Make adjustments if necessary (see System SuitabilityunderChromatography á621ñ).

Diluent— Prepare a degassed mixture of water and acetonitrile (6:4).

Standard preparation— Transfer about 25mg of USP Cefpodoxime Proxetil RS,accurately weighed,to a 50-mLvolumetric flask,dissolve in 5mLof methanol,dilute withDiluentto volume,and mix.Transfer 5.0mLof this solution to a 100-mLvolumetric flask,dilute withDiluentto volume,mix,and pass through a filter having a 0.45-µm or finer porosity.

Assay preparation— Transfer about 50mg of Cefpodoxime Proxetil,accurately weighed,to a 100-mLvolumetric flask,dissolve in 10mLof methanol,dilute with Diluent to volume,and mix.Transfer 5.0mLof this solution to a 100-mLvolumetric flask,dilute with Diluentto volume,mix,and pass through a filter having a 0.45-µm or finer porosity

Chromatographic system(seeChromatography á621ñ)— The liquid chromatograph is equipped with a 235-nm detector and a 4.6-mm ×25-cm column that contains 5-µm packing L1.The flow rate is about 2mLper minute.The column temperature is maintained at a constant temperature of about 30.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the relative retention times are about 0.9for cefpodoxime proxetil S-epimer and 1.0for cefpodoxime proxetil R-epimer;the resolution,R,between cefpodoxime proxetil S-epimer and cefpodoxime proxetil R-epimer is not less than 2.5;the tailing factor for cefpodoxime proxetilR-epimer is not more than 1.5;and the relative standard deviation determined from the sum of the areas of the cefpodoxime proxetilS-epimer and cefpodoxime proxetilR-epimer peaks for replicate injections is not more than 1.0%.

Procedure— Separately inject equal volumes (about 20µL)of theStandard preparationand theAssay preparation into the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity in µg of cefpodoxime (C15H17N5O6S2)in each mg of Cefpodoxime Proxetil taken by the formula: in which Cis the concentration,in mg per mL,of USP Cefpodoxime Proxetil RSin the Standard preparation;Pis the designated potency,in µg per mg,of cefpodoxime (C15H17N5O6S2)in USP Cefpodoxime Proxetil RS;Wis the weight,in mg,of Cefpodoxime Proxetil taken to prepare the Assay preparation;and rUand rSare the sums of the peak responses for cefpodoxime proxetil S-epimer and cefpodoxime proxetil R-epimer obtained from the Assay preparationand the Standard preparation,respectively.