A: Infrared Absorption á197Mñ.

B: The retention time of the major peak in the chromatogram of the Assay preparationcorresponds to that observed in the chromatogram of the Standard preparationobtained as directed in the Assay.

Mobile phase— Prepare a filtered and degassed mixture of 0.1Mphosphoric acid,methanol,acetonitrile,and glacial acetic acid (1700:105:105:100).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Transfer about 20mg of USP Cefotetan RS,accurately weighed,to a 100-mLvolumetric flask,add 5mLof methanol,swirl for several minutes,add 5mLof acetonitrile,and swirl until dissolved.Dilute with water to volume,and mix.

Resolution solution— Place 10mLof Standard preparationin a glass-stoppered flask containing a few mg of magnesium carbonate,and sonicate for 10minutes.If the solution is not turbid,add a few more mg of magnesium carbonate,and repeat the sonication.Filter the turbid solution through a filter of 0.5µm or finer porosity.Collect the clear filtrate,and use as the Resolution solution.

Assay preparation— Using a suitable quantity of Cefotetan,accurately weighed,proceed as directed for Standard preparation.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm ×25-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph 20µLof the Resolution solution,and record the peak responses as directed under Procedure:the relative retention times are about 0.75for cefotetan and 1.0for cefotetan tautomer,and the resolution between the cefotetan peak and the cefotetan tautomer peak is not less than 2.0.Chromatograph the Standard preparation,and record the peak responses as directed under Procedure:the column efficiency is not less than 1500theoretical plates,the tailing factor is not more than 1.5,and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the areas of the responses for the major peaks.Calculate the quantity,in µg,of cefotetan (C17H17N7O8S4)in each mg of the Cefotetan taken by the formula: in which Cis the concentration,in mg per mL,of USP Cefotetan RSin the Standard preparation,Pis the designated potency,in µg of cefotetan (C17H17N7O8S4)per mg,of USP Cefotetan RS,Mis the weight,in mg,of Cefotetan taken to prepare the Assay preparation,and rUand rSare the cefotetan peak responses obtained from the Assay preparationand the Standard preparation,respectively.