A: Infrared Absorption á197Mñ.

B: The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that in the chromatogram of the Standard preparation,as obtained in the Assay.

Mobile phase— Dissolve 5.75g of monobasic ammonium phosphate in 700mLof water,add 3.2mLof a 40%solution of tetrabutylammonium hydroxide,280mLof methanol,and 25mLof tetrahydrofuran,and mix.Adjust with phosphoric acid to a pHof 4.5±0.1,pass through a filter having a 0.5-µm or finer porosity,and degas.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Quantitatively dissolve an accurately weighed quantity of USP Cefmetazole RSin Mobile phaseto obtain a solution having a known concentration of about 200µg of cefmetazole (C15H17N7O5S3)per mL.[NOTE—Use this solution within 10minutes.]

Resolution solution— Prepare a solution of USP Cefmetazole RSin 0.01Nsodium hydroxide containing about 1mg per mL.Heat at 95for 10minutes.To 1mLof this solution add 2mLof Standard preparation,and dilute with Mobile phaseto obtain 20mLof solution.This solution contains cefmetazole and cefmetazole lactone (resolution compound).

Assay preparation— Transfer about 20mg of Cefmetazole,accurately weighed,to a 100-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.[NOTE—Use this solution within 10minutes.]

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 214-nm detector and a 4.6-mm ×25-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph the Resolution solution,and record the peak responses as directed for Procedure:the resolution,R,between cefmetazole and cefmetazole lactone is not less than 3.0.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency is not less than 1250theoretical plates;the tailing factor is not less than 0.94and not more than 1.6;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the areas for the major peaks.Calculate the quantity,in µg,of cefmetazole (C15H17N7O5S3)in each mg of Cefmetazole taken by the formula: in which Cis the concentration,in µg per mL,of cefmetazole (C15H17N7O5S3)in theStandard preparation;Mis the quantity,in mg,of Cefmetazole taken to prepare the Assay preparation;and rUand rSare the cefmetazole peak responses obtained from the Assay preparationand the Standard preparation,respectively.